How to Check Laptop Battery Health on Windows and Mac

On Windows, run the command powercfg /batteryreport and compare the battery's design capacity with its full charge capacity. On a Mac, open System Settings > Battery and look at Battery Health. Either way, you get a clear picture of how much charge the battery can still hold compared with when it was new, without installing anything.

That number matters because laptop batteries wear gradually. A machine that once lasted a full working day may manage half a morning a few years later, and it is worth knowing whether the cause is the battery itself or something else draining it.

Windows: the battery report

1. Right-click the Start button and open Terminal, PowerShell or Command Prompt.
2. Type powercfg /batteryreport and press Enter.
3. The window shows where the report was saved, usually your user folder, as a file called battery-report.html. Open it in any browser.

What to read in the report

To turn the figures into a health percentage, divide full charge capacity by design capacity and multiply by 100. A battery whose full charge capacity is 40,000 mWh against a design of 50,000 mWh is at 80 percent of its original capacity. Many laptop makers also include their own support app with a simple battery health indicator, which is worth a look if the report is missing data.

Mac: Battery Health and cycle count

1. Open the Apple menu > System Settings > Battery.
2. Click the information button next to Battery Health. You will see a condition such as Normal or Service Recommended, and on recent models a Maximum Capacity percentage.
3. For the cycle count, hold the Option key, open the Apple menu and choose System Information. Under Hardware, select Power; the cycle count is listed in the battery information.

A charge cycle is one full battery's worth of use, which may be spread over several partial charges. Each Mac model has a rated cycle count listed by Apple, so you can see how far through its expected life the battery is.

Signs the battery needs replacing

• Runtime has dropped sharply, even with the same apps and screen brightness.
• Capacity is well below design, and the capacity history shows a steady downward slope.
• Sudden shutdowns while the indicator still shows a decent percentage.
• A warning from the system, such as "Service Recommended" on a Mac or a replace-battery notice from Windows or the maker's app.
• Physical swelling: a lifting trackpad, a base that rocks on the desk, a lid that no longer closes flush, or gaps along the case seams.

Swelling is the one sign that needs immediate action. Stop using and charging the laptop, keep it somewhere cool and away from anything flammable, do not press on or puncture the case, and take it to a repair service. A swollen lithium-ion battery should never be left in daily use.

Before blaming the battery

Short runtimes are not always about wear. Check these first:

• Screen brightness, usually the biggest single drain.
• Background apps: Task Manager on Windows and Activity Monitor on a Mac both show which programs use the most energy.
• Power mode: a high-performance setting trades runtime for speed.
• Heavy workloads: video calls, large spreadsheets and video editing all draw more power. If the computer struggles generally, the guide to checking computer specs helps you see whether it is simply underpowered for the work.

Replace the battery or the laptop?

A battery swap is often worthwhile on a laptop that otherwise meets your needs: the processor is adequate, there is enough memory, and the operating system still receives updates. On an older machine that is also slow and out of support, the battery may be the moment to retire it.

In most modern laptops the battery is fixed inside the case, so replacement is a service job rather than a click-out swap. Use a genuine or properly certified part; poorly made replacement cells are a known safety risk. For several company laptops at once, a computer support company can check health across the fleet and plan replacements before batteries fail on the road.

Keeping wear in check

Heat is the biggest enemy of lithium-ion cells, so avoid using a laptop on a duvet, near a radiator or in a parked car on a warm day. Many laptops also offer a setting that holds the charge below 100 percent when the machine lives on a dock all day, which reduces wear. Phones age the same way; the matching guide to checking battery health on Android covers handsets.