mAh to Wh calculator
Multiply milliamp-hours by nominal voltage, then divide by 1,000. A 10,000 mAh rating at 3.7 V is 37 Wh. Enter the voltage printed with your capacity rating to calculate yours.
10,000 mAh at 3.7 volts equals 37 Wh.
10,000 mAh at 3.7 V
Nominal stored energy
10,000 ÷ 1,000 × 3.7 = 37 Wh
- mAh
- 10,000
- Ah
- 10
- Wh
- 37
- kWh
- 0.037
These values describe the same battery rating at 3.7 V. We round the displayed values but keep the full result when you reverse the conversion.
A 10,000 mAh rating at 3.7 V is 37 Wh. At 7.4 V, the same charge capacity is 74 Wh. Check the battery label before changing the voltage.
Compare two battery labelsUse watt-hours to compare batteries at different voltages.
Understand the conversion
Why mAh needs a voltage
A mAh rating tells you how much electric charge a battery holds. To express that rating as energy in watt-hours, you also need its nominal voltage.
A 5,000 mAh battery at 7.4 V and a 10,000 mAh battery at 3.7 V both have 37 Wh of nominal energy. Use the label comparison above to compare both batteries in Wh.
Formula and worked example
Wh = mAh × V ÷ 1,000
mAh = Wh ÷ V × 1,000
5,000 mAh × 3.7 V ÷ 1,000 = 18.5 Wh. For 10,000 mAh at the same voltage, the result is 37 Wh.
The NIST conversion reference lists ampere-hours under electric charge and watt-hours under energy. The battery calculations here use nominal label voltage.
mAh to Wh conversion table at 3.7 V
Use these values only for ratings specified at 3.7 V. Change the voltage in the calculator for a different battery. This reference table stays fixed while you edit the calculator.
| mAh | Nominal voltage | Wh |
|---|---|---|
| 1,000 | 3.7 V | 3.7 |
| 2,500 | 3.7 V | 9.25 |
| 5,000 | 3.7 V | 18.5 |
| 10,000 | 3.7 V | 37 |
| 20,000 | 3.7 V | 74 |
| 30,000 | 3.7 V | 111 |
Common questions
Which voltage should I use?
Use the nominal voltage printed with the capacity rating. For a pack rating, use the pack voltage. For a single cell, use the cell voltage. A charger's full-charge voltage or a USB port's output voltage may describe a different part of the system.
How many Wh is 10,000 mAh?
At 3.7 V, 10,000 mAh is 37 Wh. At 3.85 V, it is 38.5 Wh; at 7.4 V, it is 74 Wh. Use the voltage attached to the capacity rating, even if the device has several output voltages.
Can I reverse Wh to mAh?
Yes. Divide Wh by nominal voltage and multiply by 1,000, or use Reverse conversion above. The calculator keeps the full result when reversing and rounds only the displayed answer.