Amp Hours to Watt Hours Calculator (and the 100 Wh Airline Limit)
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Amp Hours to Watt Hours Calculator (and the 100 Wh Airline Limit) by TheCalcTools
How the Amp Hours to Watt Hours Calculator (and the 100 Wh Airline Limit) works
Watt-hours = amp-hours × voltage. Because power banks and laptops use different voltages, Wh is the fair way to compare them, and it is what airlines regulate.
Under IATA guidance, spare lithium batteries up to 100 Wh can go in cabin baggage; 100 to 160 Wh need airline approval; spares must never go in checked baggage.
The formula
Worked example
Using the default values shown in the calculator:
| Capacity | 20000 |
|---|---|
| Unit | mAh |
| Nominal voltage (V) | 3.7 |
| Load (W, for runtime) | 10 |
| Conversion efficiency | 85 % |
- 20,000 mAh at 3.7 V = 74.00 Wh: Up to 100 Wh: allowed in cabin baggage on most airlines.
- It runs a 10 W load for about 6.29 hours.
Result:
| Energy (Wh) | 74.00 |
|---|---|
| Capacity (Ah) | 20.000 |
| Runtime at the load (hours) | 6.29 |
| Airline carry-on check | Up to 100 Wh: allowed in cabin baggage on most airlines |
Frequently asked questions
Is a 20,000 mAh power bank allowed on planes?
At 3.7 V it is 74 Wh, under the 100 Wh limit, so it is usually allowed in cabin baggage.
Sources and further reading
- IATA: Lithium batteries guidance for passengers
- FAA: PackSafe, lithium batteries
- Wikipedia: Ampere hour
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