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Ah to Wh Calculator

Convert a battery's nominal capacity between amp-hours and watt-hours. Enter the battery's nominal voltage from its specifications: the same Ah value at different voltages represents different nominal energy.

Not sure what to enter? Read the step-by-step guide.

Your inputs

Switching direction clears the value so it is not interpreted using the wrong unit.

What does nominal voltage mean?
Use the rated voltage of the same battery or bank as the Ah/Wh value, not its live charging voltage.

Use ratings for the same battery or bank. Results update in this browser; no battery chemistry or voltage is assumed.

Battery capacity conversion

Your battery capacity in Wh or Ah

Estimated nominal energy

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Enter a capacity and nominal battery voltage to convert.

This conversion gives nominal Wh or Ah only. It does not estimate usable capacity, runtime, battery condition, or limits on current and power.

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See calculation details, assumptions and sources

Nominal Wh = Ah × nominal V; in reverse, Ah = nominal Wh ÷ nominal V. The voltage must be the nominal rating of the same battery or bank, not an instantaneous reading while charging or under load.

For example, 100 Ah at 12.8 V is 1,280 Wh nominal. Reversing it, 1,280 Wh ÷ 12.8 V is 100 Ah. At 25.6 V, the same 100 Ah is 2,560 Wh; Ah alone does not identify energy.

Actual usable energy can differ with battery chemistry, discharge rate, age, temperature, and the state-of-charge range you allow. For an estimate that includes a minimum battery level, use the Battery Runtime or Battery Size calculator.

Reference: Victron battery specifications list nominal V, Ah and Wh for the same battery models. See the site methodology.