How do you convert mAh to Wh?
Divide milliamp-hours by 1,000 to get amp-hours, then multiply by the cell voltage: Wh = (mAh ÷ 1000) × V. At 3.7 V, 10,000 mAh is 37 Wh.
Battery energy
mAh to Wh
A power bank's mAh rating means nothing for energy until you know the cell voltage — 10,000 mAh is 37 Wh at 3.7 V Li-ion, not 10 of anything. Set the voltage below to get the watt-hours that actually matter.
Formula
Wh = (mAh ÷ 1000) × V (watt-hours = amp-hours × voltage)
mAh
=
Energy
37 Wh
V
Tip: use the nominal voltage of one cell for a single cell, or the whole pack voltage for a battery bank.
10000 mAh ÷ 1000 × 3.7 V = 37 Wh
Reference table
Change the voltage in the calculator aboveMilliamp-hours to Watt-hours at 3.7 V
| Milliamp-hours (mAh) | Watt-hours (Wh) |
|---|---|
| 1000 mAh | 3.7 Wh |
| 2000 mAh | 7.4 Wh |
| 5000 mAh | 18.5 Wh |
| 10000 mAh | 37 Wh |
| 20000 mAh | 74 Wh |
| 50000 mAh | 185 Wh |
Why it matters
Why this conversion needs a voltage
Watt-hours are how airlines rate battery limits and how you compare power banks fairly, since mAh quietly assumes a voltage. Converting mAh to Wh at 3.7 V (the Li-ion cell standard) tells you whether a pack clears the 100 Wh carry-on limit and how it really stacks up against another.
Real-world use
Where you'll use it
Check whether a power bank is under the 100 Wh airline carry-on limit.
Compare two power banks fairly in watt-hours instead of raw mAh.
Convert a phone or laptop battery's mAh rating into stored energy.
Estimate how many phone charges a power bank delivers from its Wh.
FAQ
Common questions about mah to wh
What is 10000mAh in Wh?
At the standard 3.7 V Li-ion cell voltage, 10,000 mAh is 37 Wh. At 5 V (a rated USB output) it would be 50 Wh — so always use the cell voltage, not the USB output.
Why 3.7 volts?
Almost every mAh-rated cell is lithium-ion with a nominal voltage of about 3.7 V, so power bank capacity is measured at 3.7 V. Use that unless you know your cell is different.
What's the airline limit in mAh?
Airlines limit spare batteries to 100 Wh for carry-on without approval. At 3.7 V that's about 27,000 mAh, which is why most travel power banks stop near 26,800 mAh.
Related routes
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Unitly.fyi · results update live — set your own voltage or battery chemistry above.