# Spolvero

> Free browser tools that run on your own device: webcam, microphone, speaker, keyboard and dead pixel tests, classroom and workout timers, a voice recorder and teleprompter, bingo and tambola card generators, a poster maker, photo-to-crochet charts, a true-size ruler and ring sizer, a photo metadata (EXIF) remover, a GST calculator for India with the CGST and SGST split, speech time and exam time (minutes per mark) calculators, and astrology tools — a janam kundali, a Western birth chart, today's horoscope by Moon sign and a panchang with vrat dates, computed in the browser. No sign-up, no install, and camera, microphone and photo data is processed in the browser, not uploaded.

Spolvero is an independent studio. Every tool page states what the tool does in its first paragraph, lists the steps, and answers common questions. Each tool has at least one guide that explains the problem it solves.

## Device tests

Is the camera working? Is the mic picking you up? Are any pixels dead? Answers in seconds, with the fix underneath when the answer is no. All of them: https://spolvero.design/tools/device-tests/

- [Webcam Test](https://spolvero.design/tools/device-tests/webcam-test/): See your webcam, get a readiness score, and find out if your resolution, frame rate and lighting are good enough for a call. Nothing is uploaded — the video never leaves your browser.
- [Online Mirror](https://spolvero.design/tools/device-tests/online-mirror/): Use your webcam as a mirror: zoom in, freeze, light your face with a bright screen border, see the true un-flipped view, or match a pose with Ghost Pose. Nothing is uploaded.
- [Mic Test](https://spolvero.design/tools/device-tests/mic-test/): Speak for five seconds and get a plain answer: clear, too quiet, noisy or distorting — with playback so you hear yourself. Nothing is uploaded.
- [Speaker Test](https://spolvero.design/tools/device-tests/speaker-test/): Play a test tone through each channel and confirm the right output device is selected before your call starts.
- [Keyboard Test](https://spolvero.design/tools/device-tests/keyboard-test/): Press every key on a real layout, then catch chatter (double-typing), ghosting and stuck keys — with a mouse test alongside. Nothing is logged.
- [Mouse Test](https://spolvero.design/tools/device-tests/mouse-test/): Check every mouse button and the scroll wheel, catch a switch that double-clicks on its own, and measure clicks per second.
- [Dead Pixel Test](https://spolvero.design/tools/device-tests/dead-pixel-test/): Full-screen colour fields that make dead pixels, stuck pixels and backlight bleed easy to spot.
- [Laptop Check](https://spolvero.design/tools/device-tests/laptop-check/): One checklist for a second-hand or new laptop: screen, keyboard, trackpad, camera, mic, speakers, ports and battery, with what the browser can read about the machine, ending in a page you can print or save as a PDF.

## Timers

Countdowns big enough for the back of a classroom, Toastmasters speech lights and an exam clock. Fullscreen carries no ads at all. All of them: https://spolvero.design/tools/timers/

- [Countdown Timer](https://spolvero.design/tools/timers/countdown-timer/): A countdown for anything, from thirty seconds to ten hours. Big fullscreen digits, the time left in the tab title, and an alarm that can ring until you stop it.
- [Pomodoro Timer](https://spolvero.design/tools/timers/pomodoro-timer/): The Pomodoro Technique ready to run: 25 minutes of focus, 5-minute breaks and a long break after four, with a bell at every change and a count of today's pomodoros.
- [Classroom Timer](https://spolvero.design/tools/timers/classroom-timer/): A visual countdown built to be projected: huge digits, a shrinking ring, and a calm chime. Fullscreen carries no ads at all, so nothing unexpected appears in front of a class.
- [Speech Timer](https://spolvero.design/tools/timers/speech-timer/): Timing lights for Toastmasters meetings, presentations and contests. Pick the speech type and the green, amber and red points are set for you.
- [Exam Clock](https://spolvero.design/tools/timers/exam-clock/): A projected exam clock showing start and finish times alongside the time remaining, with an optional reading period. Nothing on screen but the clock.
- [Interval Timer](https://spolvero.design/tools/timers/interval-timer/): Rounds of work and rest with loud cues and a full-screen colour change, so you know which phase you are in without looking closely.
- [Tabata Timer](https://spolvero.design/tools/timers/tabata-timer/): The Tabata protocol ready to run: twenty seconds of work, ten of rest, eight rounds, with a lead-in and clear colour changes.
- [Debate Timer](https://spolvero.design/tools/timers/debate-timer/): Speech times and protected periods for the main debating formats, without setting them up by hand every round.

## Audio

Record, trim and export in the tab. Nothing is uploaded — the file is written on your own machine. All of them: https://spolvero.design/tools/audio/

- [Voice Recorder](https://spolvero.design/tools/audio/voice-recorder/): Record from your microphone, trim the dead air off the ends, and download an MP3 or WAV. Captured, edited and encoded on your own device — there is no server to send it to.
- [Teleprompter](https://spolvero.design/tools/audio/teleprompter/): Paste a script, turn on the camera and record while the text scrolls next to the lens — at a steady pace, or following your voice. The script and the take stay on your device.

## Play

Bingo cards and Tambola tickets to print, a caller for the TV, and phone play from one link. No accounts for anyone. All of them: https://spolvero.design/tools/play/

- [Bingo Card Generator](https://spolvero.design/tools/play/bingo-card-generator/): Your own words or 20 ready themes, 3×3 to 5×5 or 1–75 numbers. Print unique cards as a PDF, or send one link and every phone gets its own card — then call the game on the TV and check wins by card number.
- [Tambola Tickets](https://spolvero.design/tools/play/tambola-tickets/): Print Housie tickets that follow the standard rules — 15 numbers, 5 per row — three, six or twelve to a page. The caller reads each number aloud and checks early five, lines and full house from the ticket number.
- [Tambola Prize Calculator](https://spolvero.design/tools/play/tambola-prize-calculator/): Enter the ticket price and tickets sold, take out the host's share and pick the dividends. Early five, each line, full house and any extras come out rounded to ₹1, ₹5, ₹10 or ₹50, ready to copy to WhatsApp.
- [Kitty Party Chits](https://spolvero.design/tools/play/kitty-party-chits/): Lucky chits, tasks, Who am I names, icebreaker questions or your own list, printed on A4 or Letter with cut lines and a fold. Or draw them on screen with no repeats, to pick next month's host.
- [Virtual Piano](https://spolvero.design/tools/play/piano/): Play with your computer keys, a touchscreen or a MIDI keyboard. Pick a song and the next key lights up and waits for you, in Western or sargam notation — then record and download an MP3 or MIDI file.
- [Photo Jigsaw Puzzle](https://spolvero.design/tools/play/photo-jigsaw-puzzle/): Cut your own photo into a jigsaw, from 12 to 300 pieces, and solve it by dragging on a phone or computer. The photo stays on your device while you play.

## Print at home

Print any picture as a wall-sized poster on A4 or Letter, with a sharpness check before you print and a numbered map on every sheet. All of them: https://spolvero.design/tools/print/

- [Poster Maker](https://spolvero.design/tools/print/poster-maker/): Choose how big the picture should be, check it will look sharp, and download a PDF of numbered sheets with cut marks and a map on each — as a photo or as halftone dots. Made on your device; nothing is uploaded.

## Craft

Turn a photo into a crochet or knitting chart with rows written in words, then follow it on your phone with a tracker that remembers your row. All of them: https://spolvero.design/tools/craft/

- [Chart Maker](https://spolvero.design/tools/craft/crochet-pattern-from-photo/): Turn a photo into a C2C, single crochet or knitting colourwork chart with few, clean colours and true stitch proportions — with every row written out in words, yarn per colour and a printable PDF. Made on your device.
- [Row Counter](https://spolvero.design/tools/craft/row-counter/): A big tap-to-count row counter with a repeat counter, and a tracker that reads your chart to you row by row and remembers where you stopped. Kept on your device, no account.

## Measure

A real-size ruler in cm and inches, a ring sizer with Indian, US, UK and EU sizes and an Indian bangle sizer — calibrated to your own screen with a bank card. All of them: https://spolvero.design/tools/measure/

- [Ring Sizer](https://spolvero.design/tools/measure/ring-size/): Calibrate once with a bank card, lay a ring on the circle and read its size in Indian, US, UK, EU and Japanese sizes — with a full conversion chart and a printable paper sizer. Nothing is uploaded.
- [Bangle Sizer](https://spolvero.design/tools/measure/bangle-size/): Calibrate once with a bank card, lay a bangle on the circle and read its Indian size, 2-2 to 3-0, kadas included. No bangle? Type your hand measurement instead. Nothing is uploaded.
- [Online Ruler](https://spolvero.design/tools/measure/ruler/): Match an outline to any bank card and the ruler is true to size on your screen, in cm, mm and inches, across or upright. The calibration stays on your device and every measuring tool here reuses it.

## Photo

See the location, date and camera details hidden in your photos and remove them from a whole batch, or fix a wrong camera clock — with no upload and no quality lost. All of them: https://spolvero.design/tools/photo/

- [Photo Metadata Remover](https://spolvero.design/tools/photo/exif-remover/): Drop in a batch of photos to see the location, date, camera and serial number hidden in each, then remove everything or only the location and download clean copies — with no quality lost. Nothing is uploaded.
- [Change Photo Date](https://spolvero.design/tools/photo/change-photo-date/): Move the date taken on a whole batch of JPEG photos by days, hours and minutes — for a camera left on the wrong time zone — so they sort correctly everywhere. Made on your device; nothing is uploaded.

## Astrology

A janam kundali and a Western birth chart calculated in the browser, today's horoscope read from the Moon's real position, and a panchang with vrat dates for your city — the same engine as the Jyotish app. All of them: https://spolvero.design/tools/astrology/

- [Kundli Maker](https://spolvero.design/tools/astrology/kundli/): Your janam kundali from your birth date, time and place: lagna, the nine grahas by rashi, degree and nakshatra, the navamsa and the Vimshottari dasha running now. Lahiri ayanamsa, North or South Indian style, computed in your browser.
- [Birth Chart Calculator](https://spolvero.design/tools/astrology/birth-chart/): Your Western natal chart: Sun, Moon and rising sign, every planet by sign, degree and house, the major aspects, and the wheel — plus the same Sun and Moon in the Vedic zodiac so the 24° difference stops being a mystery.
- [Today's Horoscope](https://spolvero.design/tools/astrology/horoscope-today/): Today's horoscope for all twelve rashis, read the classical way: the house the Moon is crossing counted from your sign, with today's tithi and nakshatra for your place. Computed when you open it, not written in the morning.
- [Today's Panchang](https://spolvero.design/tools/astrology/panchang/): The five limbs of the day computed for your location — tithi and nakshatra with their end times, yoga, karana, vara, sunrise and sunset — the lunar month in both reckonings, and every Ekadashi, Purnima, Amavasya, Pradosh and Sankashti date for the next twelve months.

## Calculators

A GST calculator for India: add GST or remove it at 5%, 18%, 40% and the special rates, with the CGST and SGST or IGST split worked out the way an invoice needs it. A speech time calculator for words to minutes and back, and an exam time calculator for minutes per mark with a finish-by plan. All of them: https://spolvero.design/tools/calculators/

- [GST Calculator](https://spolvero.design/tools/calculators/gst-calculator/): Add GST to a price or take it out of a total at 5%, 18%, 40% and the special rates, with the tax split into CGST and SGST or shown as IGST. Same engine as the GST Calculator app. No sign-up.
- [Speech Time Calculator](https://spolvero.design/tools/calculators/speech-time-calculator/): Paste a speech or type a word count to see how long it takes to say, or start from the minutes you have and get a word target. Pace presets, pauses and slides, and words counted the way the teleprompter counts them.
- [Exam Time Calculator](https://spolvero.design/tools/calculators/exam-time-calculator/): Type the exam length, marks, reading and checking time to get minutes per mark, time per question and the clock time to finish each section by. CBSE presets checked against the board's papers.

## Guides

- [How Guna Milan is calculated: the 36 points, koota by koota](https://spolvero.design/articles/guna-milan-36-points-explained/): The eight kootas of Ashtakoota matching, what each one compares and how many points it can give, with the rules for Nadi, Bhakoot and the 18-point line.
- [How Ekadashi dates are decided: the sunrise rule, and why Smarta and Vaishnava sometimes differ](https://spolvero.design/articles/how-ekadashi-dates-are-decided/): Ekadashi is the 11th tithi, kept on the day it is running at sunrise. When it straddles two dawns, Smarta and Vaishnava households may fast on different days.
- [How to find your Moon sign (rashi) from your birth date, time and place](https://spolvero.design/articles/how-to-find-your-moon-sign/): Your Moon sign is the sign the Moon was in at your birth. It needs date, place and roughly the time, since the Moon changes sign every 2¼ days. Find it free.
- [How to read your kundli: lagna, rashi, nakshatra and dasha, in that order](https://spolvero.design/articles/how-to-read-your-kundli/): A janam kundali has four things to find first: the lagna, the Moon's rashi, its nakshatra and the dasha running now. What each is and where it sits.
- [Kundli without a birth time: what still holds, and what does not](https://spolvero.design/articles/kundli-without-birth-time/): No birth time? Your Moon sign, nakshatra and every graha's rashi still hold. The lagna, houses, navamsa lagna and dasha dates do not. What to use, what to skip.
- [Moon sign or Sun sign: which horoscope should you read?](https://spolvero.design/articles/moon-sign-vs-sun-sign-horoscope/): Western daily horoscopes use your Sun sign; Indian ones your Moon sign (rashi). Why they differ, why the Moon-sign one can change daily, and how to find yours.
- [Mulank, bhagyank and namank: how to work out your numbers](https://spolvero.design/articles/mulank-bhagyank-namank/): How Ank Jyotish works out your mulank from your birth day, your bhagyank from the full date, and your namank from your name, with the letter table and rulers.
- [Sun, Moon and rising sign: what the big three are and how to find yours](https://spolvero.design/articles/sun-moon-rising-sign-meaning/): Sun sign: where the Sun was. Moon sign: where the Moon was. Rising sign: the one on the eastern horizon at birth. What each covers and why the time matters.
- [Why your Vedic sign is different from your Western sign: the 24° ayanamsa](https://spolvero.design/articles/why-vedic-and-western-signs-differ/): Western astrology starts the zodiac at the March equinox; Vedic fixes it to the stars. They differ by about 24°, so most Vedic Sun signs are one sign earlier.
- [How long does skincare take to work? Give it four weeks at least](https://spolvero.design/articles/how-long-does-skincare-take-to-work/): Most products need four weeks or more before any change is fair to judge, longer as skin ages. How to test one product properly, with photos you can compare.
- [Which skincare ingredients should you not mix? The clashes that are real](https://spolvero.design/articles/skincare-ingredients-not-to-mix/): Retinoids with acids, benzoyl peroxide with tretinoin, too many exfoliants: the clashes worth avoiding, why, and why vitamin C with niacinamide is fine.
- ["Camera is being used by another application": how to find the app and get it back](https://spolvero.design/articles/camera-in-use-by-another-app/): Another program is holding your camera. Find which one on Windows or Mac, quit it fully, then check the camera is free in a browser webcam test.
- [How many jigsaw pieces? A guide by age, time and screen](https://spolvero.design/articles/how-many-jigsaw-pieces/): 48 pieces take most adults 5 to 15 minutes on screen; 1,000 take several evenings. The right piece count by age, plus a free photo jigsaw maker.
- [How to time an exam: start, finish, reading time and extra time](https://spolvero.design/articles/how-to-time-an-exam/): Start the clock when the paper begins, time reading separately, add extra time to the finish: 25% on 2 hours is 30 minutes. Free exam clock, no sign-up.
- [Keyboard ghosting test: what ghosting and n-key rollover mean, and how to check yours](https://spolvero.design/articles/keyboard-ghosting-n-key-rollover/): Why some key combinations drop a press, what 2KRO, 6KRO and NKRO mean, how many keys you actually need at once, and how to test your keyboard in a browser.
- [How to play a MIDI keyboard in your browser, with no software](https://spolvero.design/articles/midi-keyboard-in-browser/): Yes, a USB MIDI keyboard works in Chrome, Edge and Firefox, not Safari. Plug in, press Connect MIDI and play with touch sensitivity. Free, no sign-up.
- [Bangle size chart (India): inches, mm and hand size](https://spolvero.design/articles/bangle-size-chart-india/): Every Indian bangle size from 2-0 to 3-0 with the inner diameter in inches and mm, the inside circumference, and the largest hand each size passes over.
- [Debate speech times by format: BP, World Schools, Lincoln-Douglas and Model UN](https://spolvero.design/articles/debate-speech-times-by-format/): Speech lengths, protected time and points of information for British Parliamentary, World Schools, Lincoln-Douglas and Model UN, with how to time each one.
- [Does coffee count as water intake? What the hydration trial found](https://spolvero.design/articles/does-coffee-count-as-water-intake/): A 2016 trial found coffee, tea, juice and soft drinks hydrate no differently from water. What it measured, what it left out, and how to count your cups.
- [How long is a 1,000-word speech? Times from 500 to 2,000 words](https://spolvero.design/articles/how-long-is-a-1000-word-speech/): A 1,000-word speech takes about 6 minutes 40 seconds to 7 minutes 42 seconds at a normal pace. Times for 500 to 2,000 words, with pauses and slides.
- [How many words for a 60-second video script, and how to write one that reads well](https://spolvero.design/articles/how-many-words-60-second-video-script/): At 140 to 160 words a minute, a 60-second video is about 140 to 160 words. Word counts for 15 to 180 seconds, and how to write a script that sounds spoken.
- [How many words is a 5-minute speech? Word counts from 1 to 20 minutes](https://spolvero.design/articles/how-many-words-in-a-5-minute-speech/): A 5-minute speech is about 650 to 750 words at a normal pace. Word counts from 1 to 20 minutes, how to find your own pace, and how to time a practice run.
- [How much water should I drink a day? What EFSA, the IOM and ICMR-NIN actually say](https://spolvero.design/articles/how-much-water-should-i-drink-a-day/): Published figures are for total water, food included. Take off the share you eat and most adults need 1.5 to 3 litres of drinks a day, not eight glasses.
- [How to divide Tambola prize money: the split, the rounding and the host's share](https://spolvero.design/articles/how-to-divide-tambola-prize-money/): Split a Tambola pool fairly: 10% early five, 15% per line, 45% full house. How to take out the host's share, add extras and round so the total is exact.
- [How to measure bangle size at home: three ways, best first](https://spolvero.design/articles/how-to-measure-bangle-size-at-home/): Measure a bangle you own on a calibrated screen, measure your hand with the thumb tucked in, or use a ruler. Which size to pick when you fall between two.
- [How to organise Tambola at home: tickets, calling and prize money](https://spolvero.design/articles/how-to-organise-tambola/): Everything a Tambola host needs: how many tickets to print, how to split the prize pool, how to call numbers at the right pace and how to check a claim.
- [How to pick the next kitty party host fairly, every month](https://spolvero.design/articles/how-to-pick-next-kitty-host/): Three fair ways to choose the next kitty host: a monthly chit draw, a full order drawn once a year, or a fixed rota. Plus swaps, new members and missed months.
- [How to split a 3-hour exam: a section-by-section time plan for CBSE papers](https://spolvero.design/articles/how-to-split-a-3-hour-exam/): A section-by-section time plan for a 3-hour CBSE paper, with finish-by times from 10:30 to 1:30, for 80-mark Maths and 70-mark Physics.
- [Indian ring size chart, with US, UK and EU sizes side by side](https://spolvero.design/articles/indian-ring-size-chart-us-uk-eu/): What an Indian ring size measures, the full conversion to US, UK and EU sizes with diameters in mm, and why two jewellers' charts can disagree by a size.
- [Kada size for men: how to measure it, and the size chart](https://spolvero.design/articles/kada-size-guide/): Kada sizes use the same 2-N scale as bangles. How to measure a kada or your hand at home, the sizes in inches and mm, and how loose a kada should sit.
- [Kitty party chit games: six games for a bowl of folded chits](https://spolvero.design/articles/kitty-party-chit-games/): Six kitty party chit games: lucky chits, task chits, Who am I, icebreaker questions, the next host draw and turn order. How to run each, and print the chits.
- [Kitty party games: 12 ideas that work for eight to twenty ladies, and how to run Tambola](https://spolvero.design/articles/kitty-party-games-ideas/): Twelve kitty party games from one-minute challenges to a full Tambola round, how long each takes, what to give as prizes and how to keep it to two hours.
- [Minutes per mark: how to plan your time in an exam](https://spolvero.design/articles/minutes-per-mark-exam-time/): Divide your writing time by the total marks to get minutes per mark. Worked examples for 1-hour to 3-hour papers, CBSE included, and how to use the figure.
- [Tambola prize ideas: what to give for each win, in money or in gifts](https://spolvero.design/articles/tambola-prize-ideas/): Tambola prize ideas for home, kitty and office games: how to split a cash pool, gifts for each win, and which wins should get the biggest prize.
- [Tambola prize money for 20, 50 and 100 players: worked examples](https://spolvero.design/articles/tambola-prize-money-examples/): Ready-made Tambola prize splits for 20, 50 and 100 players at ₹20, ₹50 and ₹100 a ticket, with a host's share and extras, each adding up to the last rupee.
- [Toastmasters timing rules: green, amber and red for every speech type](https://spolvero.design/articles/toastmasters-timing-rules/): What the timing lights mean, the exact times for every speech type, and the 30-second rule that disqualifies contestants. Plus how to run the timer role.
- [Words per minute for speeches: how fast to talk, and how to find your own pace](https://spolvero.design/articles/words-per-minute-for-speeches/): Most prepared speeches run at 130 to 150 words a minute. What the figures mean, how to measure your own pace in a minute, and how to write to it.
- [Clicks per second: what counts as a good CPS score, and how to test it](https://spolvero.design/articles/clicks-per-second-test/): Normal clicking reaches 6 to 8 clicks per second. What jitter and butterfly clicking add, why a fast score can hide a faulty mouse, and how to test your CPS.
- [Why does a flashlight app want camera permission? It does not need it](https://spolvero.design/articles/flashlight-app-camera-permission/): Android has had a direct torch API since version 6 that needs no camera permission. Why some torch apps still ask, and how to check one before you install it.
- [HSN code: how to find it, and the GST rate that goes with it](https://spolvero.design/articles/hsn-code-gst-rate/): What an HSN or SAC code is, how many digits your invoice needs, and how to find the right code and GST rate for a product without guessing.
- [Keyboard keys not working or typing twice: how to find out why](https://spolvero.design/articles/keyboard-keys-not-working/): A dead key, a key that types twice and a key that repeats on its own are three different faults. How to tell them apart in two minutes, and what fixes each one.
- [How to send SOS with your phone flashlight, and how long each flash should be](https://spolvero.design/articles/sos-signal-phone-flashlight/): SOS in light is three short flashes, three long, three short. The right timing, how to send it by hand or with an app, and what a flashing phone cannot do.
- [Webcam blurry or grainy? It is almost never the camera](https://spolvero.design/articles/webcam-blurry-or-grainy/): A blurry or grainy webcam is usually short of light, not broken. The fixes in order of impact, and a free webcam test to measure the difference.
- [Breakfast, lunch and dinner in Tambola: what they mean and how to check a claim](https://spolvero.design/articles/breakfast-lunch-dinner-in-tambola/): Breakfast, lunch and dinner are three Tambola prizes for the left, middle and right thirds of the ticket. The numbers each covers and when each is won.
- [ATM and credit card size in cm, mm and inches, and how to use a card as a ruler](https://spolvero.design/articles/credit-card-size-cm-inches/): Every ATM, debit and credit card is 8.56 × 5.398 cm (85.6 × 53.98 mm, or 3.370 × 2.125 inches). How to measure with one and set a screen ruler.
- [Tambola games list: 15 prize patterns for kitty parties and family nights](https://spolvero.design/articles/tambola-games-list/): Beyond early five and full house: fifteen Tambola prize patterns, what each one needs on the ticket, and how many to play in one game so it does not drag.
- [How to change your phone torch brightness on Android](https://spolvero.design/articles/change-phone-torch-brightness-android/): Android 13 added torch brightness levels, but only some phones support them. How to tell if yours does, how to dim the flash, and what to use if it cannot.
- [How to check laptop battery health on Windows, Mac and Chromebook](https://spolvero.design/articles/check-laptop-battery-health/): Read your laptop battery's real capacity and cycle count with tools already on it: powercfg on Windows, System Information on Mac, Diagnostics on Chromebook.
- [How to check a monitor or laptop screen before the return window closes](https://spolvero.design/articles/check-screen-before-return-window/): A ten-minute check for a new or used screen: dead, hot and stuck pixels, backlight bleed and uniformity, what counts for a return, and how to record it.
- [How to check a used laptop before you buy it](https://spolvero.design/articles/how-to-check-a-used-laptop-before-buying/): The checks that catch faults sellers do not mention: screen, keys, trackpad, camera, mic, speakers, ports, battery health and account locks. About 15 minutes.
- [CGST, SGST or IGST: which one goes on your invoice, and how to split it](https://spolvero.design/articles/cgst-sgst-igst-which-applies/): Within a state, GST splits into equal CGST and SGST. Across state lines it is one IGST line at the full rate. How to tell which applies, with worked splits.
- [GST on gold jewellery: 3%, making charges, and how to check the bill](https://spolvero.design/articles/gst-on-gold-jewellery/): Gold jewellery carries 3% GST, a rate GST 2.0 left alone. How making charges are taxed, where the 5% rate applies, and how to check a jeweller's bill.
- [GST on a restaurant bill: how to check it's charged right](https://spolvero.design/articles/gst-on-restaurant-bill/): Most restaurants charge 5% GST, as 2.5% CGST and 2.5% SGST. When 18% is right, why service charge is optional, and how to check a bill in thirty seconds.
- [How to calculate GST: add it to a price, or take it out of a total](https://spolvero.design/articles/how-to-calculate-gst/): The two GST formulas, adding to a price and extracting from a total, with worked examples at 5%, 18% and 40%, and the mistake that overstates the tax.
- [What is a tithi? Why Hindu festival dates move every year](https://spolvero.design/articles/what-is-a-tithi/): A tithi is a lunar day: the time the Moon takes to move 12° from the Sun. Thirty make a lunar month, they last 19–26 hours, and they make festival dates shift.
- [Christmas Tambola for the office party: rules, calls and how to run it for fifty people](https://spolvero.design/articles/christmas-tambola-office-party/): How to run Christmas Tambola at an office party: tickets for a big room, prizes that suit colleagues, festive number calls and a claim check that takes seconds.
- [Diwali Tambola party: how to host it, what to give as prizes and what to print](https://spolvero.design/articles/diwali-tambola-party-ideas/): A Diwali Tambola plan for a family or office party: how many tickets to print, how to split the pot, prizes to give and how to keep a round to 30 minutes.
- [Halloween bingo: how to run it for a class or a party, with words, patterns and prizes](https://spolvero.design/articles/halloween-bingo-party-ideas/): How to run Halloween bingo for children or adults: the word list, card size by age, five winning patterns, how many rounds, and unique cards in a minute.
- [New Year's Eve party games for the whole family: what to play before midnight](https://spolvero.design/articles/new-year-party-games-for-family/): Games that work from age six to seventy on New Year's Eve: Tambola and bingo you can print, quick rounds for the hour before midnight, and how to run them.
- [Printable Tambola tickets PDF: how to make them free, and when a ready kit is worth it](https://spolvero.design/articles/printable-tambola-tickets-pdf/): How to print proper Tambola (Housie) tickets as a PDF for free, what a correct ticket looks like, how many to a page, and what a paid party kit adds on top.
- [How long should a power nap be? 10, 20 or 90 minutes](https://spolvero.design/articles/how-long-should-a-power-nap-be/): Ten to twenty minutes is the power nap that leaves you alert. Why longer naps leave you groggy, when 90 minutes makes sense, and how to wake on time.
- [25/5, 50/10 or 52/17: how long to focus before taking a break](https://spolvero.design/articles/how-long-to-focus-before-a-break/): Pomodoro's 25/5, the hour-shaped 50/10 and DeskTime's 52/17 compared: where each comes from, what kind of work each suits, and how to find your own rhythm.
- [How long to steep tea: black, green, oolong, white and herbal](https://spolvero.design/articles/how-long-to-steep-tea/): Black tea 3 to 5 minutes, green 1 to 3 at a lower heat, herbal 5 to 7. A chart of steeping times and temperatures, and why tea left too long turns bitter.
- [The Pomodoro Technique: what it is and how to do it properly](https://spolvero.design/articles/what-is-the-pomodoro-technique/): 25 minutes of focus, a 5-minute break, a long break after four. Where the Pomodoro Technique came from, the rules most people skip, and how to start today.
- [How to check your yoga pose at home with a webcam, no mirror wall needed](https://spolvero.design/articles/check-yoga-pose-with-webcam/): No studio mirror? Use your laptop camera: freeze a reference pose, lay it over the live picture as a ghost, and line up hips, shoulders and hands against it.
- [Classroom bingo: 10 ways to use it for sight words, maths and vocabulary](https://spolvero.design/articles/classroom-bingo-ideas/): Ten ways to use bingo as a review game across subjects, how to call it so the whole class thinks, and how to make a set of unique cards in minutes.
- [How to find someone's ring size secretly: five ways that work](https://spolvero.design/articles/find-ring-size-secretly/): Five ways to get a partner's ring size without asking, from borrowing a ring for a minute to asking a friend, ranked by accuracy, with mistakes to avoid.
- [How to find your Sa: choosing the right scale for your voice](https://spolvero.design/articles/find-your-sa-for-singing/): Sa is not a fixed note. Here is how to find the one that suits your voice in ten minutes, what White 1 and Black 2 mean, and how to check it with a drone.
- [The camera clock was wrong: how to fix the date on a whole batch of photos](https://spolvero.design/articles/fix-wrong-date-on-photos/): A camera on the wrong time zone puts every photo out by the same amount. How to work out the gap and shift the date taken on a batch, without uploading.
- [Hands-free row counting: use a foot pedal, page turner or keyboard](https://spolvero.design/articles/hands-free-row-counter-foot-pedal/): Count rows without putting your yarn down. How a Bluetooth page turner, foot pedal or keyboard works with an online row counter, and keeping the screen awake.
- [Headphones only working on one side: find the fault in two minutes](https://spolvero.design/articles/headphones-only-one-side-working/): Sound in one ear only is a plug, a cable, a port, a setting or the headphones. Two swaps and a left-right test tell you which, before you buy anything new.
- [How big can I print my photo? Pixels, PPI and viewing distance](https://spolvero.design/articles/how-big-can-i-print-a-photo/): The largest print a photo can make from its pixel width, why a poster needs far fewer pixels per inch than a small print, and why WhatsApp photos print small.
- [How long should a brain break be? Timings, ideas and how to end one](https://spolvero.design/articles/how-long-should-a-brain-break-be/): Two to five minutes is the working range for a classroom brain break. How often to run one, what to do in it, and how a visible timer brings the class back.
- [How to do a mock exam at home that actually prepares you](https://spolvero.design/articles/how-to-do-a-mock-exam-at-home/): A mock only helps if it copies the real conditions: full length, one sitting, a visible finish time and no help. How to set one up at home and what to do after.
- [How to fix a stuck pixel, and when a pixel cannot be fixed](https://spolvero.design/articles/how-to-fix-a-stuck-pixel/): A stuck pixel sometimes recovers with rapid colour cycling or gentle pressure. A dead one never does. How to tell them apart, what to try, and when to stop.
- [How to host virtual bingo on Zoom or Teams, with a card on every phone](https://spolvero.design/articles/how-to-host-virtual-bingo-on-zoom/): Run bingo on any video call: one link gives every player their own card on their phone, you call from a shared tab, and wins are checked by card number.
- [How to read a C2C crochet graph, and how big and how much yarn](https://spolvero.design/articles/how-to-read-a-c2c-graph/): C2C is worked in diagonal rows from one corner. How to read a graph row by row, how many squares make a throw or a twin blanket, and how much yarn to buy.
- [How to keep track of rows in crochet and knitting](https://spolvero.design/articles/keep-track-of-rows-crochet-knitting/): Six ways to count rows, from pen marks to a row counter that remembers your place, how to track pattern repeats, and how to find your row when you lose count.
- [How to measure something without a ruler, using what is in your wallet](https://spolvero.design/articles/measure-without-a-ruler/): Bank cards, A4 paper and coins are made to exact sizes. How to use them as a ruler, how to turn your screen into an accurate one, and how far to trust each.
- [How to print a large poster on A4 paper at home, step by step](https://spolvero.design/articles/print-large-poster-on-a4/): Tile any picture across A4 or Letter sheets, print it at the right scale, and join the pages so the seams hardly show. Printer settings, paper, glue, trimming.
- [How to read from a teleprompter without looking like you are reading](https://spolvero.design/articles/read-teleprompter-naturally/): Moving eyes, a flat voice and a chased pace give a script away. How to place the text, write for the ear, set words per minute and record a natural take.
- [How to put photos from two cameras or phones into one timeline](https://spolvero.design/articles/sync-photos-from-two-cameras/): Photos from a camera and a phone, or from two guests, land out of order when their clocks disagree. How to find the offset for each and line them all up.
- [Tabata for beginners: how to build up to the full 20/10 in six weeks](https://spolvero.design/articles/tabata-for-beginners/): The full Tabata is a hard first session. Scale the rest, not the effort: start at 20 seconds on and 40 off, and shorten the rest over several weeks until 20/10.
- [How to turn a photo into a crochet pattern that keeps its shape](https://spolvero.design/articles/turn-photo-into-crochet-pattern/): Choosing the photo, stitch, size and colours for a graphghan, why faces come out stretched on square-grid charts, and how much yarn to buy.
- [What is a rasterbated poster? How halftone dot wall art works](https://spolvero.design/articles/what-is-a-rasterbated-poster/): A rasterbated poster rebuilds a photo from dots that grow where it is dark. Why it works from small photos, which dot size to pick, and how to print one.
- [What is an EMOM workout? How it works, and how to set one up](https://spolvero.design/articles/what-is-an-emom-workout/): EMOM means every minute on the minute: start a set of work at the top of each minute and rest for what is left. How to choose the work, the length and variants.
- [What is EXIF data? What your photos reveal, and how to see it](https://spolvero.design/articles/what-is-exif-data/): EXIF is the hidden information a camera writes into every photo: date, camera, settings and often GPS. What each field gives away and how to view or remove it.
- [What Tabata training really is: the 20/10 protocol and the study behind it](https://spolvero.design/articles/what-is-tabata-training/): Tabata is eight rounds of 20 seconds' work and 10 seconds' rest: four minutes. What the 1996 study did, why gym versions are easier, and how to do one properly.
- [Why knitting charts come out stretched, and how gauge fixes it](https://spolvero.design/articles/why-knitting-charts-come-out-stretched/): A knit stitch is wider than it is tall, so a square-grid chart grows about 40% taller when knitted. How to chart colourwork to your gauge so it keeps its shape.
- [Why you look different in photos than in the mirror](https://spolvero.design/articles/why-you-look-different-in-photos/): The mirror shows you flipped, and that is the face you know. Why the true view looks wrong, which one other people see, and how to check it before a call.
- [Work-to-rest ratios for interval training: how to choose yours](https://spolvero.design/articles/work-to-rest-ratios-interval-training/): 40/20, 30/30, EMOM or 1:3 sprints: what each work-to-rest ratio is for, how hard the work should feel, and how to set it on a timer you can read across a room.
- [Mouse double-clicking on a single click: how to confirm it and what fixes it](https://spolvero.design/articles/mouse-double-clicking-fix/): A mouse that double-clicks by itself is usually a worn switch, not Windows. How to prove it in a minute, rule out the software causes, and the fixes that last.
- [How to remove the location from a photo before you share it](https://spolvero.design/articles/remove-location-from-photos/): A photo can carry the GPS coordinates of your home. What is hidden in the file, where it survives, and how to remove it on iPhone, Windows, Mac or in a browser.
- [8 easy piano songs for beginners, with the notes and computer keys](https://spolvero.design/articles/easy-piano-songs-for-beginners/): Eight songs a complete beginner can play today, in order of difficulty, with the letter notes and the computer keys that play them on an online piano.
- [How to solve a jigsaw puzzle faster: 9 methods that work](https://spolvero.design/articles/how-to-solve-jigsaw-faster/): Edges first is only the start. Sorting by colour and by shape, building islands, and what to do with a sky that is all one blue — on the table and on a screen.
- [How to cancel a subscription on Android, including the ones Google Play cannot see](https://spolvero.design/articles/cancel-subscription-android/): Cancel a Play subscription in four taps, find the ones billed outside Play, and understand why deleting the app changes nothing about what you are charged.
- [How to stop a free trial turning into a subscription you did not want](https://spolvero.design/articles/free-trial-turned-into-subscription/): Free trials convert automatically by design. How to find the exact conversion date, cancel without losing the trial, and what to do after a charge lands.
- [How to split subscriptions fairly when several people use them](https://spolvero.design/articles/split-subscriptions-household/): Why an even split is usually the wrong one, how to compare monthly and annual plans honestly, and which services actually allow sharing before you rely on it.
- [How long should classroom activities actually take?](https://spolvero.design/articles/classroom-activity-timings/): Realistic durations for think-pair-share, group work, silent reading and tidy-up, and why a visible timer changes behaviour more than saying the time aloud.
- [How to compress a photo without uploading it to a stranger's website](https://spolvero.design/articles/compress-photo-without-uploading/): Online compressors take a copy of your photo first. How to hit an upload size limit with tools already on your phone or computer, and keep the file.
- [MP3, WAV, M4A or OPUS: which audio format to pick, and when](https://spolvero.design/articles/mp3-vs-wav-vs-m4a/): A plain comparison of the formats you actually meet — what each is for, how big it gets, where it plays, and the one rule that avoids most mistakes.
- [How to record a decent voice-over with just a laptop mic](https://spolvero.design/articles/record-voiceover-laptop-mic/): Seven changes that improve a laptop-mic recording more than new hardware does — room, distance, levels and the one setting that quietly ruins takes.
- [How to find every subscription you pay for, without handing over a bank login](https://spolvero.design/articles/track-subscriptions-without-bank-login/): Most subscription trackers want your banking credentials first. How to find everything you pay for without that, and what those apps really get.
- [720p, 1080p or 4K: what a webcam actually needs to be](https://spolvero.design/articles/720p-1080p-4k-webcam/): Meeting apps cap what they will send long before a 4K webcam becomes useful. Here is what each resolution is really worth, and what to spend on instead.
- [Camera not working in Chrome? 7 fixes, in the order that works](https://spolvero.design/articles/camera-not-working-chrome/): Chrome can't find your camera, shows a black screen, or says it's blocked. Here are the seven fixes, ordered by how often each one is the answer.
- [Is my laptop camera hacked? How to actually check](https://spolvero.design/articles/is-my-laptop-camera-hacked/): Camera hijacking is rarer than the headlines suggest, but not impossible. How to check properly on Windows and Mac, and what the light tells you.
- [How to look good on Zoom using things you already own](https://spolvero.design/articles/look-good-on-zoom-lighting/): You do not need a ring light. A lamp, a window and a stack of books will do more for how you look on a video call than any camera upgrade.
- [The five-minute camera check before a video interview](https://spolvero.design/articles/webcam-test-before-interview/): A short, ordered checklist for the minutes before a video interview — camera, light, framing, sound and the backup plan for when something fails anyway.

## Optional

- [Every tool and guide in full](https://spolvero.design/llms-full.txt): the text of each tool page and guide in one file
- [All tools](https://spolvero.design/tools/): the directory, grouped by category
- [About Spolvero](https://spolvero.design/about/): who makes the tools
- [Privacy](https://spolvero.design/privacy/): what is and is not collected