What this converter does
This converter turns watt-hours into milliampere-hours and back. Because energy is charge times voltage, you must enter the battery voltage — 3.7 V is the default for a lithium cell. Type a value and read the result as you type.
Power banks are labelled in both Wh and mAh, and mixing them without the voltage gives wrong answers. This tool keeps them consistent.
The units it covers
Energy (Wh) and charge (mAh) are linked by the battery voltage — energy is charge times voltage.
View all units & their values
| Unit | Symbol | Value | Mainly used |
|---|---|---|---|
| Watt-hour | Wh | energy | Battery/pack energy capacity |
| Milliampere-hour | mAh | charge | Cell/phone battery rating |
| Voltage | V | input | Nominal battery voltage |
The formula
Energy equals charge times voltage, so watt-hours and milliampere-hours are related through the pack voltage:
Wh = mAh × V ÷ 1000Where:
- Wh = energy in watt-hours
- mAh = charge in milliampere-hours
- V = nominal battery voltage
Worked example
Convert 10 Wh at 3.7 V to mAh.
mAh = Wh × 1000 ÷ V10 × 1000 ÷ 3.7 = 2,703 mAhSo a 10 Wh cell at 3.7 V holds about 2,703 mAh.
The units in this example
A unit of energy — the true capacity of a battery, independent of voltage. Airlines rate packs in Wh.
- 1 Wh = 1,000 mWh
- 1 Wh = 0.001 kWh
- Wh = mAh × V ÷ 1000
- 10 Wh @3.7V = 2,703 mAh
A unit of electric charge — how phone and cell batteries are usually rated. Only comparable at the same voltage.
- 1,000 mAh = 1 Ah
- mAh = Wh × 1000 ÷ V
- 2,000 mAh @3.7V = 7.4 Wh
- mAh × V ÷ 1000 = Wh