Windows has a built-in command that creates a full health report on your laptop battery. Most people never run it. They should.
The command is powercfg /batteryreport. Open the Start menu, type "cmd", right-click Command Prompt, then click "Run as administrator" and paste it in. Windows builds a web-page file and tells you where it saved it. Double-click that file and you get a multi-page breakdown: every charge cycle (one full drain and recharge), how worn the battery is since the day you bought the laptop, and the gap between what your battery is rated to hold and what it actually holds today.
Yeah, it's that easy. The command ships with every Windows 10 and Windows 11 install. No download, no third-party app, no signup.
What you actually see
The report shows two numbers that matter. "Design Capacity" is how much charge your battery held when it was brand new. "Full Charge Capacity" is how much it can hold right now. If those two numbers are close, your battery is in good shape. If Full Charge Capacity is way below Design Capacity, your battery is worn out.
Example. A two-year-old ThinkPad might show a Design Capacity of 57,000 mWh and a Full Charge Capacity of 41,000 mWh. (mWh, or milliwatt-hours, is just the unit the report uses to measure battery size. Bigger number means more charge.) That works out to 72% health. Below 80% is when most people start noticing the laptop dies way faster than it used to.
The report also draws every recent charge cycle as a graph, so you can see exactly when your battery started dropping faster. That is genuinely useful if you suspect a recent Windows update or some bad app is draining the battery overnight while the lid is closed.
Why this matters
There are three real-world reasons to actually run this.
- Buying a used laptop. Run the command before you hand over money. If the seller swears the battery is "great" but the report shows 60% health, you have hard evidence on screen that the battery is more than a third worn and the thing will not hold a charge anywhere near what the listing promised.
- Warranty claims. If your laptop is still under warranty and the battery sits below the maker's stated limit (usually 80% within the first year), the report is the exact evidence support will ask for.
- Knowing when to replace. Battery swaps cost between $80 and $200 depending on the laptop. The report tells you whether you actually need one, or whether the battery is fine and your bad runtime is really a software problem.
This should honestly be a standard step before every used-laptop purchase on Facebook Marketplace or eBay. It takes 30 seconds.
The Linux version
Linux laptops have the same trick. The command is upower -i $(upower -e | grep BAT). It dumps the same kind of info straight to your terminal. The output is uglier (no tidy web-page report), but the numbers are all there. Look for "energy-full" versus "energy-full-design" near the top of the output. That ratio is your battery health: what it holds now versus what it held when new.
macOS users can check the same thing in System Information under the Power section. Apple actually shows this right in the menus, so no command needed.
The catch
The report is only as accurate as your battery's own internal sensor. Some cheap laptops and a lot of off-brand replacement batteries report wildly wrong numbers. If the report says 100% health on a five-year-old laptop, the sensor is lying. Cross-check against real-world use. If you used to get 8 hours and now you barely get 3, your battery is worn no matter what the report claims.
Brand new laptops will also show a flat line for the first week or two. The tool can't plot a wear trend without a few charge cycles of data, so wait until you've actually used the machine before you draw any conclusions.
Try it right now
Open Command Prompt as administrator and paste this.
powercfg /batteryreport /output "%USERPROFILE%\Desktop\battery.html"
That drops the report straight on your desktop as battery.html. Double-click to open it in your default browser.
Wait, one more. Try powercfg /energy in the same window. Same idea but for power use across your whole system. It tells you which apps are draining your laptop when it should be sitting idle, and which drivers are misbehaving in the background. Combine those two reports and you basically have a free, built-in toolkit for checking laptop battery life that Microsoft just buried.
