Watt-hours to Amp-hours Calculator

What is a watt-hours to amp-hours calculator?

A watt-hours to amp-hours calculator converts a quantity of energy into a charge capacity for a given operating voltage. Watt-hours (Wh) describe how much energy a battery stores or a load consumes, while amp-hours (Ah) describe how much electric charge flows at a fixed voltage. Battery datasheets, solar setups, and power banks frequently quote capacity in one unit when you need the other, and this tool bridges the two.

Because amp-hours depend on the voltage at which the energy is delivered, you always need both the energy figure and the system voltage to make the conversion.

How does it work?

Energy equals charge multiplied by voltage, so charge equals energy divided by voltage. Dividing the watt-hours by the volts gives the amp-hours directly:

Here $Ah$ is the charge in amp-hours, $Wh$ is the energy in watt-hours, and $V$ is the voltage in volts.

How to use

1. Enter the energy in watt-hours (Wh).
2. Enter the voltage of the battery or system in volts (V).
3. Read the charge capacity in amp-hours (Ah). The result appears automatically once both fields are filled.

The voltage must be greater than zero — dividing energy by a voltage of zero has no physical meaning.

Worked examples

A 100 Wh battery operating at 12 V holds:

A 60 Wh pack at the same 12 V works out to a clean whole number:

The higher the voltage, the fewer amp-hours the same energy represents: the energy is unchanged, but it is delivered with less current over time.

Practical notes

Manufacturers often list power banks in milliamp-hours (mAh) at a low cell voltage such as 3.7 V, even though the energy you actually get out depends on the voltage your device runs at. Converting through watt-hours keeps the comparison honest, because energy is the quantity that stays fixed regardless of voltage.

To reverse the calculation and find energy from a known charge and voltage, use the amp-hours to watt-hours calculator. For power and current relationships at a given voltage, the watts to amps calculator and the kWh to watts calculator handle the related conversions.