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Battery capacity converter

Use the watt-hour rating and nominal voltage for the same battery. This reverses the energy calculation so you can understand the units on its documentation.

How the calculation works

Capacity (Ah) = energy (Wh) ÷ nominal voltage (V).

Use the result with care

Rounding on a label can affect the result. This is a unit calculation, not a test of a battery’s actual capacity. Matching calculated Ah or voltage does not establish tool or charger compatibility. Do not use a maximum marketing voltage in place of nominal voltage.

Your figures stay in this page

The calculation runs in your browser. These entries are not sent to a calculator service or saved by this tool. Reset returns the form to its starting values.