mAh to Wh calculator
Page updated · Sources and review method
Watt-hours tell you how much energy a battery stores. Airlines use this number to set capacity limits.
Use nominal battery voltage. For example, 20,000 mAh × 3.7 V ÷ 1,000 = 74 Wh. A 100 W USB output rating tells you charging power, not stored energy.
Worked examples at 3.7 V
- 5,000 mAh18.5 Wh
- 10,000 mAh37 Wh
- 20,000 mAh74 Wh
- 26,800 mAh99.16 Wh
- 30,000 mAh111 Wh
- 50,000 mAh185 Wh
Last checked 2026-11-04
Power bank flight checker
Enter the capacity and voltage from your label to see your result.
Power bank flight FAQs
Quick answers before you pack.
Can I bring a power bank on a plane?
Generally, a power bank up to 100 Wh can travel in carry-on baggage, subject to the operating airline’s quantity, labelling and route requirements. It must not go in checked baggage. Above 100 Wh, check whether the airline accepts it with approval; above 160 Wh is not allowed in passenger baggage.
How do I convert mAh to watt-hours?
Multiply capacity in mAh by the battery’s nominal voltage, then divide by 1,000. At 3.7 V, a 20,000 mAh power bank is 74 Wh. Use the voltage on your battery label.
Can I put a power bank in my checked bag?
No. Power banks belong in the cabin. If your carry-on is checked at the gate, remove your power banks first.
Is a 100 Wh power bank always allowed?
No blanket guarantee applies. Many airlines allow up to 100 Wh, but quantity, labelling, recall status and local rules also matter. Check your operating airline.
Do the rules change when I connect?
Yes. Every operating airline and departure or transit airport can impose requirements. Check every leg and meet all applicable rules.