Battery Atlas

Conversions

Battery Capacity Unit Converter

Convert between mAh, Ah, coulombs, Wh and kWh. Energy units need a voltage.

V

Formula

1 Ah = 1000 mAh = 3600 C
Wh = Ah × V,  kWh = Wh ÷ 1000

Worked example

2,500 mAh at 3.7 V = 2.5 Ah = 9,000 C = 9.25 Wh.

Limitations and warnings

  • CCA, CA, MCA and reserve capacity (RC) are not capacity units and cannot be converted here.

Four values that are often confused

Nominal capacity (Ah)
Charge a battery delivers under rated conditions, usually over 20 hours (C20) at 25 °C.
Usable capacity
The part of the nominal capacity you can use without damaging the battery — about 50% for lead-acid, 80–90% for LiFePO4.
Cranking current (CCA)
Current deliverable for a short time in the cold to start an engine. It measures power, not stored charge, and cannot be converted to Ah.
Stored energy (Wh)
Ah × voltage. The right unit to compare batteries of different voltages.