mAh to Wh Converter
Convert battery capacity between mAh and watt-hours, and check airline power bank limits.
About the mAh to Wh Converter
mAh (milliamp-hours) measures charge; watt-hours measure energy, which also depends on voltage. Airlines regulate by watt-hours: under IATA and FAA rules, spare lithium-ion batteries and power banks up to 100 Wh are allowed in carry-on, 100–160 Wh need airline approval, and above 160 Wh are forbidden on passenger planes. A 20,000 mAh power bank at 3.7 V is 74 Wh.
The formula
Wh = mAh × V ÷ 1000
Worked example
Example: Energy = 90.2 Wh
- Inputs: Convert: mAh → Wh; Capacity: 22,000 mAh; Nominal voltage: 4.1 V.
- Formula: Wh = mAh × V ÷ 1000
- Result: Energy = 90.2 Wh
Questions people ask
Is a 27,000 mAh power bank OK to fly?
At 3.7 V it's 99.9 Wh, just under the 100 Wh limit.
Why does a 20,000 mAh bank not charge my phone 5 times?
Voltage conversion to 5 V and losses mean about 60–70% reaches the phone.