Enter a battery's amp-hour rating and its nominal voltage to convert that capacity into kilowatt-hours of stored energy.
How to Use the Amp-Hours to Kilowatt-Hours Calculator
Enter the amp-hour rating printed on the battery, then check the voltage field — it's prefilled at 12 V for a typical lead-acid or LiFePO4 deep-cycle battery, but change it to match whatever pack is actually in front of you. The energy total in kWh recalculates immediately below.
An Amp-Hour Isn't an Energy Figure by Itself
Amp-hours measure charge moved over time, not energy — the number on a battery's label tells you nothing about how much work that battery can do until a voltage gets attached to it. This trips people up because Ah looks like a complete spec on its own, the way kWh or Wh would be, but it isn't; two batteries can share an identical Ah rating and still store wildly different amounts of energy.
Energy (kWh) = (Amp-Hours × Voltage) ÷ 1,000A 200 Ah battery at 12 V — a common size for a single deep-cycle marine or solar battery — stores 2.4 kWh. Wire four of those cells in series to build a 48 V bank and the same 200 Ah rating on the label now represents 9.6 kWh, four times the energy, because the voltage did the multiplying, not the amp-hours. Whatever voltage this calculator uses is the whole story; change it and the result scales exactly in proportion, with nothing else in the math adjusting to compensate.