mAh to Wh Converter — Battery Capacity to Watt-Hours
CalculatorAn mAh to Wh converter multiplies battery capacity (mAh) by voltage (V) and divides by 1000 to get energy in watt-hours.
What is it
mAh (milliampere-hour) measures charge, so the same mAh stores different energy at different voltages. Wh (watt-hour) accounts for voltage and is the unit airlines use for battery rules (typically up to 100Wh in carry-on, 100-160Wh with airline approval). Lithium-ion cells have a nominal voltage of 3.7V (3.6-3.85V depending on the product); use the voltage printed on your battery when available.
How to use
- 1Enter the battery capacity in mAh.
- 2Enter the nominal voltage (3.7V for typical lithium-ion).
- 3Press calculate to see Wh and whether it is within the 100Wh limit.
Reference
| Battery | Energy |
|---|---|
| Phone 4,000mAh 3.7V | 14.8Wh |
| Power bank 10,000mAh 3.7V | 37Wh |
| Power bank 20,000mAh 3.7V | 74Wh |
| Power bank 26,800mAh 3.7V | 99.16Wh |
Sources & standards
FAQ
How many Wh is a 20,000mAh power bank?
At a nominal 3.7V, 20,000 × 3.7 / 1000 = 74Wh, which is within the common 100Wh airline carry-on limit.
Why do airlines use Wh instead of mAh?
Because mAh is a charge unit whose energy depends on voltage. Wh reflects the actual stored energy, which is what battery safety rules are based on.
Is mAh to Wh input sent to a server?
No. This calculator runs in your browser and does not send input to a server.