mAh to Wh Calculator

WORKED EXAMPLE

Example: 10,000 mAh at 3.7 V

For a hypothetical label pairing 10,000 mAh with 3.7 V, energy is 10,000 × 3.7 ÷ 1,000 = 37 Wh. The 3.7 V value is an example, not a universal power-bank voltage.

WORKED EXAMPLE

Example: 20,000 mAh and the reverse conversion

At an assumed nominal 3.7 V, 20,000 mAh equals 74 Wh. Reversing the same example gives 74 × 1,000 ÷ 3.7 = 20,000 mAh. A different nominal voltage changes the answer.

Keep capacity and voltage on the same basis

Use the voltage that belongs to the stated mAh figure. Do not multiply advertised internal-cell capacity by a USB output voltage such as 5 V. Multi-cell packs can list several different figures; consult the manufacturer if the matching capacity and voltage are unclear.

A printed Wh rating is already an energy rating

If the manufacturer provides Wh, use that figure directly when comparing stored energy. Converting it back to mAh requires its matching nominal voltage. Neither conversion measures the energy actually delivered to a device after conversion losses.

The result is a unit conversion

It does not establish charger compatibility, the number of phone recharges, or permission to carry a battery on a flight. For travel, check the operating airline’s current policy and the manufacturer’s marked rating.