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How to check laptop battery health on Windows, Mac and Chromebook

6 min read
A closed MacBook Air on a wooden surface
Photo by Howard Bouchevereau on Unsplash

The short answer

On Windows, open Command Prompt, run powercfg /batteryreport and compare Full charge capacity with Design capacity; the lower figure divided by the higher is the battery's health. On a Mac, hold Option, open the Apple menu, choose System Information, then Power, and read Cycle count and Condition. On a Chromebook, open the Diagnostics app. A website can read only the current charge, not the health.

Check the whole laptop

Battery charge tells you how full the battery is now. Battery health tells you how much it can hold compared with when it was new, and that is the number that decides how long a laptop lasts away from the wall. Every laptop keeps it, and none of them puts it on the main screen.

Health is worth checking before you buy a used laptop, when a laptop starts dying early, and before you pay for a new battery you may not need. The laptop check has a step for it, with these instructions, and a notes box for the figures.

Windows 10 and 11: the battery report

Windows writes a full battery history if you ask for it.

  1. Open the Start menu, type cmd and open Command Prompt.
  2. Type powercfg /batteryreport and press Enter.
  3. Windows says where it saved battery-report.html, usually in your user folder. Open it in any browser.

Under Installed batteries you will find two figures in milliwatt-hours. Design capacity is what the battery held new. Full charge capacity is what it holds now. Divide the second by the first: 42,000 out of 56,000 is 75%. The same section often shows a Cycle count, the number of full charges the battery has been through, though some laptops leave it blank.

Further down, Battery capacity history shows the full charge figure over time, and Battery life estimates shows how long the laptop has lasted on battery. A sudden drop in either is worth a closer look.

macOS: System Information

  1. Hold the Option key and click the Apple menu.
  2. Choose System Information.
  3. Under Hardware, choose Power.

Health Information lists the Cycle Count and the Condition. On recent versions of macOS, System Settings > Battery also shows Battery Health, with the maximum capacity as a percentage on Macs with Apple silicon.

Apple publishes its own figure: current MacBook batteries are designed to keep up to 80% of their original capacity at their maximum cycle count, which is 1,000 for most models. A Mac that shows Service Recommended has fallen short of that, or has a fault.

ChromeOS: the Diagnostics app

Open the launcher and search for Diagnostics, or go to Settings > About ChromeOS > Diagnostics. The battery card shows the battery’s health as a percentage and its cycle count, and can run a discharge test.

Why a website cannot do this

Browsers expose a little about the battery to pages: Chrome and Edge report the charge level and whether the laptop is plugged in, which the laptop check shows in its specs card. Safari and Firefox report nothing. None of them report design capacity, full charge capacity or cycle count, so any website that claims to measure battery health is guessing from how fast the charge falls.

What the numbers mean in practice

A battery at 75% of design capacity runs for about three quarters as long as it did new, under the same use. That may be fine for a laptop that lives on a desk and useless for one carried to lectures all day. The figure keeps falling with cycles, heat and time, faster when the laptop is kept at 100% and warm.

Watch for physical signs too. A trackpad that no longer sits flat, a case that has opened at the seams, or a laptop that rocks on a desk can all mean a swollen battery. Stop using it, keep it off charge, and have the battery replaced: a swollen lithium-ion battery can catch fire.

Before you buy, or before you replace

Buying second-hand, run the report on the seller’s laptop and write both figures into the notes of the laptop check, so the printed record shows what you were sold. Replacing your own, compare the health figure with how long the laptop actually lasts: if it reads 85% but dies in an hour, the cause may be a background app or brightness, not the battery. The same habit of measuring before replacing applies to a keyboard that types twice and a screen with a stuck pixel.

  • Laptop
  • Battery

Questions people ask

How do I check battery health on Windows 11?

Open Command Prompt, type powercfg /batteryreport and press Enter. Windows saves a battery-report.html file and prints where. Open it, find Installed batteries, and compare Full charge capacity with Design capacity. Full charge divided by design, times 100, is the health as a percentage.

How do I see my MacBook's battery cycle count?

Hold the Option key, click the Apple menu and choose System Information. Under Hardware, choose Power. Health Information lists the Cycle Count and the Condition, such as Normal or Service Recommended.

Can a website check my laptop's battery health?

No. Chrome and Edge let a page read the battery's current charge and whether it is charging, and that is all. Health, design capacity and cycle count are only available to the laptop's own system tools.

What battery health is too low?

There is no single cut-off. Apple designs current MacBook batteries to keep up to 80% of their original capacity at their maximum cycle count, which is 1,000 for most models, and shows Service Recommended when a battery falls short. A battery at 60% of design capacity runs for about 60% as long as it did new.

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