mAh to Wh calculator
Milliamp-hours mean nothing without a voltage. Watt-hours are the honest unit, and the one airlines actually regulate.
mAh
V
V
%
Energy
74.00Wh
- Usable energy after conversion
- 62.90 Wh
- Effective mAh at the output voltage
- 12 580
- Energy in joules
- 266 400
- Rough full phone charges Taking a phone battery as 15 Wh.
- 4.19
- Under the 100 Wh airline limit
- 1
Show the working
- Capacity = 20 000
- Cell voltage = 3.7
- Output voltage = 5
- Conversion efficiency = 85
- Energy = 20 000 * 3.7 / 1000 = 74
- Usable energy after conversion = 74 * 85/100 = 62.9
- Effective mAh at the output voltage = 62.9 * 1000 / 5 = 12 580
- Energy in joules = 74 * 3600 = 266 400
- Under the 100 Wh airline limit = 74 <= 100 ? 1 : 0 = 1
- Rough full phone charges = 62.9 / 15 = 4.193 33
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- Wh = mAh x V / 1000
- output mAh = usable Wh x 1000 / output voltage
A 20 000 mAh power bank is 74 Wh at the cell voltage of 3.7 V, not 100 Wh, and delivers about 12 000 mAh at 5 V.
The IATA limit is 100 Wh in cabin baggage without approval, and 160 Wh with it.