How the conversion works
Watt-hours are energy; amp-hours are charge. Multiplying charge by the battery's nominal voltage gives energy: Wh = Ah × V. The reverse, Ah = Wh ÷ V, converts an energy figure back to capacity at a chosen voltage.
For example, a 100 Ah battery at 12 V nominal stores 1,200 Wh. The same 1,200 Wh at 24 V corresponds to 50 Ah — which is why amp-hours alone cannot compare batteries of different voltages.
What the conversion does not tell you
The result is nominal stored energy, not what you can draw in practice. Usable energy depends on depth of discharge, and real voltage moves with the state of charge and load. For a runtime estimate that applies those factors, use the Battery Runtime calculator.
Typical nominal voltages
| Battery type | Nominal voltage | 100 Ah in Wh |
|---|---|---|
| Li-ion cell (NMC) | 3.6–3.7 V | 360–370 Wh |
| LiFePO4 cell | 3.2 V | 320 Wh |
| 12 V lead-acid / LiFePO4 pack | 12 V / 12.8 V | 1,200 / 1,280 Wh |
| 24 V system | 24 V | 2,400 Wh |
| 48 V system | 48 V | 4,800 Wh |
Methodology
The conversion is exact for the voltage you enter; the judgement is in choosing that voltage. The calculator UI, examples and displayed formula all call the same conversion function.