Battery & Energy

Battery Capacity Calculator

Battery Capacity Calculator. Battery energy, capacity and simple runtime estimates with explicit usable-capacity assumptions. Calculations run in your browser. Entered electrical values are not uploaded to our server.

Inputs

Battery voltage

Load power

W / kW

Required runtime

Usable capacity / efficiency

Calculations run in your browser. Entered electrical values are not uploaded to our server.

ⓘMathematical estimate only. Verify equipment datasheets, manufacturer instructions, electrical codes and qualified design before real-world use.

Formula & method

Required Wh = load W × runtime / usable factor; Ah = required Wh / voltage

Worked example

120 W for 9 h at 12 V and 90% usable → 100 Ah

Assumptions & safety boundary

Mathematical estimate only. Verify equipment datasheets, manufacturer instructions, electrical codes and qualified design before real-world use.