mAh to Wh converter
Battery capacity in mAh means little until you know the voltage. Watt-hours let you compare batteries of different chemistries and check airline limits.
At or under 100 Wh, generally allowed in carry-on as a spare (not in checked bags). Airlines may add their own limits.
Why convert to watt-hours?
mAh only measures charge. A 3,000 mAh 3.7 V phone cell (11.1 Wh) holds far less energy than a 3,000 mAh 12 V pack (36 Wh). Watt-hours include voltage, so they compare directly.
Wh = mAh × V ÷ 1000 · Wh = Ah × V| mAh | 3.7 V | 7.4 V | 12 V | 12.8 V |
|---|---|---|---|---|
| 1,000 | 3.7 | 7.4 | 12 | 12.8 |
| 2,500 | 9.3 | 18.5 | 30 | 32 |
| 5,000 | 18.5 | 37 | 60 | 64 |
| 10,000 | 37 | 74 | 120 | 128 |
| 20,000 | 74 | 148 | 240 | 256 |
| 26,800 | 99.2 | 198.3 | 321.6 | 343 |
| 50,000 | 185 | 370 | 600 | 640 |
| 100,000 | 370 | 740 | 1,200 | 1,280 |
Watt-hours. Power banks list capacity at the internal cell voltage (usually 3.6–3.7 V); output at 5 V USB is lower after conversion losses.
Questions people ask
How do I convert mAh to Wh?
Wh = mAh × V ÷ 1000. A 20,000 mAh power bank with 3.7 V cells holds 74 Wh.
Which voltage should I use?
Use the nominal cell or pack voltage printed on the battery: 3.6–3.7 V for most lithium-ion cells, 3.2 V for LiFePO4, 12.8 V for a 4-cell LiFePO4 pack, 12 V for lead-acid.
What is the airline limit for power banks?
The FAA and IATA allow spare lithium-ion batteries up to 100 Wh in carry-on baggage; 100–160 Wh needs airline approval; spare lithium batteries are not allowed in checked bags. Check your airline before flying.