# How to check a used laptop before you buy it Source: https://spolvero.design/articles/how-to-check-a-used-laptop-before-buying/ Updated: 2026-10-01 Tool: https://spolvero.design/tools/device-tests/laptop-check/ > Check a used laptop on the laptop itself, with the seller there, before you pay. Run a dead pixel test, press every key, test the trackpad clicks, turn on the camera and record from the mic, play each speaker, plug something into every port, read the battery's full charge capacity against its design capacity, and make sure the seller has signed out of their Apple or Microsoft account. It takes about fifteen minutes. A used laptop hides its faults well. The seller has had months to get used to the key that needs pressing twice, and none of it shows in the photos. Fifteen minutes on the laptop itself, before any money changes hands, finds most of what goes wrong. Do every check on the laptop you are buying. Open the browser on that machine, not on your phone. The [laptop check](/tools/device-tests/laptop-check/) walks you through each test below in order, keeps your marks while you open each test in another tab, and prints a one-page record at the end. ## Bring three things A USB stick or a phone with its cable, wired earphones, and the laptop's charger if the seller has not got it out. Without something to plug in, you cannot tell a dead port from a working one, and ports are a common fault on laptops that have been carried around for years. ## The screen Turn the brightness up, go fullscreen with a [dead pixel test](/tools/device-tests/dead-pixel-test/), and step through every colour. A dot that stays black on every colour is a dead pixel; one that stays red, green or blue is stuck. On the black screen, look at the edges for light leaking in, which is backlight bleed. The guide to [checking a screen before the return window closes](/articles/check-screen-before-return-window/) explains what is normal and what is a fault. Look at the screen from the side, too. Lines, a yellow patch or a pressure mark from the keyboard (on a laptop that was closed on something) all show best at an angle. ## The keyboard and trackpad Press every key in a [keyboard test](/tools/device-tests/keyboard-test/laptop/). Every key you press should light up once. A key that stays dark is not reaching the computer; a key that lights twice from one press is chattering, and the guide to [keys not working or typing twice](/articles/keyboard-keys-not-working/) explains each fault. Laptop keyboards are expensive to replace because on many models the keyboard is riveted to the top case. Then click the trackpad: left, right, and a minute of single clicks in the [mouse test](/tools/device-tests/mouse-test/). A button that sends a double click from one press is wearing out. ## Camera, mic and speakers Turn on the camera in the [webcam test](/tools/device-tests/webcam-test/) and check the picture is clear and the frame rate holds. Record a sentence in the [mic test](/tools/device-tests/mic-test/) and play it back; it tells you if the mic is quiet, noisy or distorted. Play each side in the [speaker test](/tools/device-tests/speaker-test/) and listen for a dead side or a rattle at high volume. ## Ports and charging Plug the USB stick or phone into every port and check the laptop sees it. Plug the earphones into the audio jack and play something. Plug in the charger and watch for the charging light or icon, then wiggle the plug gently: a charge that comes and goes means a worn socket. ## The battery This is the check most buyers skip and the one that costs most later. A browser can read the battery's current charge but not its health, so use the laptop's own report. On Windows, open Command Prompt and run `powercfg /batteryreport`, then open the file it names and compare **Full charge capacity** with **Design capacity**. On a Mac, hold Option, open the Apple menu, choose System Information, then Power. [How to check laptop battery health](/articles/check-laptop-battery-health/) goes through every system and what the numbers mean. ## Locks and accounts A laptop still tied to the seller can be unusable. Ask them to sign out of their Microsoft account or Apple ID and reset the laptop in front of you. On a Mac with Apple silicon or a T2 chip, Find My must be off: otherwise Activation Lock asks for the seller's Apple ID password after the Mac is erased. On any laptop, restart it and press the setup key (often F2, Del or Esc) to see whether the firmware asks for a password. ## The body Open and close the lid; it should hold any angle. Look for cracks around the hinges, missing screws and a trackpad that sits higher at one edge, which can mean a swollen battery underneath. A swollen battery is a safety problem, not a bargaining point. ## What fifteen minutes cannot tell you No browser test sees the health of the hard drive or SSD, the temperatures under load, or water damage inside the case. For the disk, the maker's diagnostics (Dell SupportAssist, HP PC Hardware Diagnostics, Lenovo Vantage) can run a check. For everything else, a return window or a short warranty is the protection. Keep the printed result from the [laptop check](/tools/device-tests/laptop-check/) with the receipt: it records what worked on the day you bought it. ## Questions ### What should I check when buying a used laptop? The screen for dead pixels and backlight bleed, every key, the trackpad and its clicks, the webcam, the microphone, both speakers, every port and the charger, the battery's health against its design capacity, the hinges and body, and that the seller has signed out of their Apple ID or Microsoft account. ### How do I check a used laptop's battery? On Windows, run powercfg /batteryreport in Command Prompt and compare Full charge capacity with Design capacity. On a Mac, hold Option, open the Apple menu, choose System Information, then Power, and read Cycle count and Condition. A website cannot read battery health. ### How can I tell if a used MacBook is locked? Ask the seller to sign out of their Apple ID and turn off Find My in front of you. A Mac with Apple silicon or a T2 chip that still has the seller's Find My on is protected by Activation Lock, and will ask for their Apple ID password after it is erased. ### Can I check a used laptop online without installing anything? Mostly. A browser can test the screen, keyboard, trackpad, camera, microphone and speakers, and read the screen resolution, processor threads and graphics. It cannot read battery health, disk health or temperatures, so those need the laptop's own tools. ### How long does it take to check a second-hand laptop? About fifteen minutes: ten for the tests, a few for the battery report, and a minute or two looking over the hinges, ports and body.