WINDOWS TOOLS · ENGLISH
Windows 11 Battery Health Calculator: Check Capacity
Check the capacity your Windows laptop reports
Use two values from a Windows battery report to compare the battery’s reported full charge capacity with its design capacity. Then separate a capacity question from a charging-limit or fast-drain problem.
1. Generate and open the report
- Open Start, type Command Prompt, right-click it and select Run as administrator. Follow your organization’s access rules on a managed PC.
- In Command Prompt, enter this command and press Enter:
powercfg /batteryreport
- Read the saved file location printed by the command. In File Explorer, go to that location and open the HTML report in your browser. Do not assume it is on your Desktop.
- Find Installed batteries and read DESIGN CAPACITY and FULL CHARGE CAPACITY for the same battery. If there is more than one battery, calculate each separately.
Microsoft documents both the report steps and the powercfg command. The command creates an HTML file in the current working directory unless you specify an output path. This page does not need your report uploaded.
2. Compare the two capacity values
Design capacity is the estimated capacity of a new battery of that type. Full charge capacity is the capacity currently reported for a full charge. It is different from the battery percentage in your taskbar. Use numbers from the same report and battery, in the same unit.
This tool calculates in your browser. It does not upload a report, send these numbers, or save your inputs.
Reported capacity ratio
Enter both capacity values and their shared unit to see the calculation.
Percentage rounded to two decimal places. This is a ratio of reported values, not a runtime prediction, a safety test or a warranty decision.
Microsoft defines the design capacity and capacity ratio and the full charge capacity. Some devices report mAh rather than mWh; do not infer the unit from the size of the number.
Illustrative arithmetic: 40,000 mWh ÷ 50,000 mWh × 100 = 80%. This says the reported full charge capacity is 80% of the design value. It does not say the taskbar is at 80%, or that every workload will run for 80% of its original time.
3. Follow the symptom, not a universal health score
A result of 100% does not prove the battery is unworn. Microsoft notes that some battery controllers can return the same value for design and full charge capacity, or no design value at all. If a value is zero, blank or unavailable, this tool cannot determine the ratio.
The reported capacity is below design
Check the same battery in reports saved on different dates. A persistent reduction is a reason to investigate capacity, especially if usable runtime no longer meets your needs. Use your laptop manufacturer’s diagnostics for your exact model before deciding on service.
The result is above 100%
The full charge value entered exceeds the design value. The tool keeps that result visible. Recheck the battery column, units and numbers; if they match, record it as “reported above design.” This calculation cannot establish why, or prove better-than-new battery health.
Capacity looks similar, but charge drains quickly
In Windows 11, open Settings → System → Power & battery → Battery usage to review usage by app. Compare a similar workload and display brightness when checking runtime. Microsoft’s battery-saving guidance explains these settings; availability varies by hardware and Windows version.
Charging stops below 100% while plugged in
A charging limit is a different question from the capacity ratio. Smart charging can intentionally limit the charge level. Features and controls depend on the device manufacturer and model. Check the matching official support page rather than assuming every laptop has the same switch.
For a service decision, use the exact laptop model and battery part number, then check the manufacturer’s support options for your country. This page does not apply a universal replacement percentage, price or warranty rule.