Battery Capacity Calculator

Calculate Capacity (Wh) Watt-hours (Wh) is the effective capacity of the battery pack, calculated by multiplying the charge capacity (Ah or mAh) by the nominal voltage (V).

Charge (Ah/mAh)

Voltage (V)

Calculate Charge (Ah/mAh) Charge (Ah or mAh) is the charge capacity of the battery pack, calculated by dividing the effective capacity (Wh) by the nominal voltage (V).

Watt-hours (Wh)

Voltage (V)

Calculate Voltage (V) Voltage (V) is the nominal voltage of the battery pack, calculated by dividing the effective capacity (Wh) by the charge capacity (Ah or mAh).

Watt-hours (Wh)

Charge (Ah/mAh)

About the battery capacity calculator

This tool calculates battery capacity, voltage, and charge and converts units between Ah and mAh.

Using the calculator

This battery-capacity calculator is divided into three tools: a capacity calculator (Wh), a charge calculator (Ah/mAh), and a voltage calculator (V).

Enter any two known values (Wh, Ah/mAh, or V) into the corresponding input fields.
The calculator will automatically determine the third value.
If needed, you can switch between Ah and mAh units.

Key terms

Watt-hours (Wh): Total energy stored. Think of it as how much work the battery can do. A 100Wh battery can output 100 watts for one hour, or 50 watts for two hours.

Amp-hours (Ah): How long a battery sustains a current. A 10Ah battery delivers 10 amps for one hour, or 5 amps for two hours. Smaller batteries use milliamp-hours (mAh), where 1000mAh = 1Ah.

Voltage (V): Electrical pressure between terminals. Higher voltage means more push behind each electron.

Calculating watt-hours

The basic relationship is straightforward:

Wh = Ah × V

For milliamp-hours, divide by 1000 first:

Wh = mAh × V / 1000