Turn a power bank’s mAh into watt-hours (Wh) — and see whether it can fly in your hand luggage.
Most power banks print “3.7V” or “3.85V” on the label next to the mAh rating.
37 Wh
Carry-on: allowed (up to 100 Wh).
Flying limits from the IATA lithium battery guidance for passengers; airlines may be stricter.
Watt-hours = mAh × volts ÷ 1,000. Airlines judge batteries in Wh, not mAh, because Wh is the energy stored — a 10,000 mAh bank with 3.7 V cells holds 37 Wh.
Multiply the capacity in mAh by the cell voltage and divide by 1,000. Most power banks use 3.7 V cells, so 10,000 mAh × 3.7 V ÷ 1,000 = 37 Wh.
Usually yes: at 3.7 V it holds 74 Wh, under the 100 Wh limit for carry-on bags. It must go in your hand luggage, never in checked bags.
Under IATA guidance, spare lithium batteries up to 100 Wh are allowed in carry-on bags; 100–160 Wh need the airline’s approval (two at most); over 160 Wh are not allowed. Airlines can set stricter rules — check yours.
Spare lithium batteries must travel in the cabin so that a fault can be seen and dealt with. That applies to every power bank, whatever its size.