Why voltage matters
mAh describes charge, not energy. Two batteries with the same mAh can store different Wh if their voltages differ.
battery capacity converter
Battery Capacity Converter
Power banks and battery packs are often labeled in mAh or Ah, while runtime math needs Wh. Convert the label first, then size the load.
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Voltage presets
Use the voltage printed on the battery label when available. mAh without voltage cannot be compared fairly.
Converted capacity
27,027 mAhmAh = Wh x 1000 / volts
Watt-hours100 Wh
Amp-hours27.03 Ah
Milliamp-hours27,027 mAh
Voltage3.7 V
Travel check: At or below 100 Wh, lithium-ion spare batteries are within the standard FAA PackSafe size limit, but airline, route, and damage-protection rules still apply. Check the FAA PackSafe lithium battery page and your airline before flying with spare batteries or power banks.
Use Wh for runtime
Runtime calculators need watt-hours because load is measured in watts and runtime is measured in hours.
Check the label
When a battery lists both mAh and Wh, prefer the printed Wh rating for travel and runtime planning.