Amp Hour Calculator | Battery Capacity Calculator, Ah↔Wh (12V–48V)

Use our Amp Hour Calculator and Battery Capacity Calculator to convert Ah ↔ Wh, size LiFePO4 and lead-acid battery banks, and estimate runtime for 12V, 24V, 36V, and 48V systems.

Enter your device watts, hours per day, system voltage, inverter efficiency, and depth of discharge (DoD)—the tool instantly returns required capacity in Ah/Wh/kWh and expected runtime.

Perfect for solar, RV, marine, golf cart, and off-grid power planning, it supports series/parallel banks and days of autonomy so you can right-size with confidence.

Use it to compare results to our Epoch LiFePO4 batteries and other packs, or quickly run amp hour to watt hour and watt hour to amp hour conversions (Ah = Wh ÷ V; Wh = W × h). 

Fast, accurate, and free!