How do you convert Wh to mAh?
Divide watt-hours by the cell voltage to get amp-hours, then multiply by 1,000: mAh = (Wh ÷ V) × 1000. At 3.7 V, 37 Wh is 10,000 mAh.
Battery energy
Wh to mAh
To turn an energy figure in watt-hours into the mAh you'd see on a spec sheet, divide by the cell voltage and scale up — 37 Wh is 10,000 mAh at 3.7 V. Set your voltage below.
Formula
mAh = (Wh ÷ V) × 1000 (milliamp-hours = amp-hours × 1000)
Wh
=
Charge
270270.27 mAh
V
Tip: use the nominal voltage of one cell for a single cell, or the whole pack voltage for a battery bank.
1000 Wh ÷ 3.7 V × 1000 = 270270.27 mAh
Reference table
Change the voltage in the calculator aboveWatt-hours to Milliamp-hours at 3.7 V
| Watt-hours (Wh) | Milliamp-hours (mAh) |
|---|---|
| 1 Wh | 270.27027 mAh |
| 5 Wh | 1351.35 mAh |
| 10 Wh | 2702.7 mAh |
| 50 Wh | 13513.51 mAh |
| 100 Wh | 27027.03 mAh |
| 500 Wh | 135135.14 mAh |
| 1000 Wh | 270270.27 mAh |
Why it matters
Why this conversion needs a voltage
Power banks are marketed in mAh, but energy limits and comparisons live in watt-hours — so converting Wh back to mAh at 3.7 V tells you the headline number a product would advertise, and lets you match a target energy to a real-world capacity rating.
Real-world use
Where you'll use it
Find the mAh rating that matches an energy target in watt-hours.
Translate the 100 Wh airline limit into a maximum mAh capacity.
Match a laptop battery's Wh to an equivalent mAh power bank.
Sanity-check a suspicious mAh claim by converting from stated Wh.
FAQ
Common questions about wh to mah
How many mAh is 100Wh?
At 3.7 V, 100 Wh is about 27,000 mAh. That's the airline carry-on ceiling, which is why travel power banks cluster just under 27,000 mAh.
Which voltage should I use?
Use the cell voltage, normally 3.7 V for lithium-ion. Don't use the 5 V USB output — that describes the port, not the cells that store the energy.
Why do two power banks with the same Wh show different mAh?
Because mAh depends on the internal cell voltage. A pack built on a higher-voltage arrangement shows fewer mAh for the same watt-hours, so always compare in Wh.
Related routes
Keep going
Unitly.fyi · results update live — set your own voltage or battery chemistry above.