mAh to Wh Calculator for Air Travel
Airlines measure power bank capacity in Watt-hours (Wh), but most power banks display milliamp-hours (mAh). You need to convert mAh to Wh to know if your power bank is flight-safe.
The Formula
Wh = (mAh × V) ÷ 1,000
Where:
Why 3.7V?
You might notice your power bank outputs 5V (USB-A) or even 20V (USB-C PD). However, airlines and regulators use the nominal cell voltage -- the internal battery voltage -- which is 3.7V for standard lithium-ion/lithium-polymer cells. Some high-capacity cells use 3.85V.
Using output voltage (5V) would give a higher Wh number and might make your power bank appear non-compliant when it actually is. Stick with 3.7V unless your power bank label specifically states a different Wh rating.
Quick Reference Table
| mAh | Wh (at 3.7V) | Airline Status |
|---|---|---|
| 5,000 | 18.5 | Allowed |
| 10,000 | 37.0 | Allowed |
| 15,000 | 55.5 | Allowed |
| 20,000 | 74.0 | Allowed |
| 25,000 | 92.5 | Allowed |
| 26,800 | 99.2 | Allowed (borderline) |
| 27,000 | 99.9 | Check with airline |
| 30,000 | 111.0 | Needs approval |
| 40,000 | 148.0 | Needs approval |
| 43,243 | 160.0 | Maximum allowed |
| 50,000 | 185.0 | Prohibited |
What If My Power Bank Shows Wh Directly?
Some newer power banks print the Wh rating directly on the label -- usually near the mAh rating. If your power bank shows Wh, use that number directly. It's more accurate than converting from mAh because the manufacturer has accounted for the exact cell voltage.
Pro Tip: Check the Fine Print
Look at the bottom or back of your power bank for a label or engraving. You'll typically find:
The mAh or Wh rating is what matters for airlines. Use our free calculator to check any power bank against 200+ airline rules instantly.
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