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Practical guide · Windows

Check battery capacity in Windows

Windows can create a battery report with powercfg /batteryreport. Full charge capacity divided by design capacity, multiplied by 100, gives the reported capacity as a percentage of its original specification.

Use the toolView the steps
Illustrative photograph of an intact laptop battery beside an open computer
AI-generated topic image. Not a model-specific repair manual.

Step by step

  1. Open Command Prompt

    Search for Command Prompt in Start, right-click it and choose Run as administrator. On a work computer, you may need your IT administrator's help.

  2. Create the report

    Enter the command below and press Enter. Windows displays the path to the HTML file saved on your computer.

    powercfg /batteryreport

  3. Find the two capacity figures

    Open the file through File Explorer and find Design Capacity and Full Charge Capacity under Installed batteries. Use figures for the same battery in the same unit.

  4. Calculate and compare with daily use

    Enter both figures in this page's calculator, which uses whole mWh. Compare the result with how long the computer actually lasts away from its charger.

Calculate battery capacity

Values from your battery report

Use values from the same battery, in mWh.

The capacity when new.

Reported capacity when fully charged.

Whole mWh: 50000, 50,000, 50.000 or 50 000. 50 Wh = 50,000 mWh.

Calculated on your device. Your values are not sent to Kestro.

Your result

Your capacity appears here once you enter both values and calculate.

Calculated from your values. This is not the current charge or a diagnosis.

Formula: Full Charge Capacity ÷ Design Capacity × 100

What does it mean?

Capacity and charge are different figures

A 100% charge means full relative to the battery's current capacity. It does not mean the battery stores as much energy as when it was new.

Missing figures? Leave them unknown

Calculate each battery separately if the computer has more than one. If capacity is missing or the result exceeds 100%, check the report and units before drawing a conclusion.

The result calculates reported capacities; it is not a physical safety test or a battery-life guarantee. If the battery is visibly swollen, stop using the device and get help with safe replacement.

Your next step

Sources and documentation

Sources

  1. 01
    Powercfg: batteryreport

    Microsoft Learn · Read

  2. 02
    Caring for your battery in Windows

    Microsoft Support · Read

  3. 03
    How to check your Surface battery capacity

    Microsoft Support · Read

  4. 04
    Handling swollen lithium-ion batteries

    Dell · Read