4,000 mAh to watt-hours
14.8 Wh
4,000 mAh at 3.7 V (lithium-ion cell voltage) · allowed in carry-on (under 100 Wh)
4,000 mAh by voltage
| Nominal voltage | Energy |
|---|---|
| 1.2 V | 4.8 Wh |
| 3.2 V | 12.8 Wh |
| 3.7 V | 14.8 Wh |
| 3.85 V | 15.4 Wh |
| 5 V | 20.0 Wh |
| 7.4 V | 29.6 Wh |
| 12 V | 48.0 Wh |
Wh = mAh × V ÷ 1000. Power banks rate mAh at the 3.6-3.7 V cell voltage, not 5 V USB output.
What it can charge
With about 65% real-world efficiency to the device: ~0.6 charges of a 15 Wh phone, ~0.2 of a 60 Wh laptop.
FAQ
How many Wh is 4,000 mAh?
14.8 Wh at 3.7 V.
Can I fly with a 4,000 mAh power bank?
At 15 Wh, yes, under the 100 Wh limit; keep it in carry-on, not checked bags.