Wh to Ah calculator
Divide watt-hours by nominal battery voltage to get amp-hours. A 480 Wh battery is 40 Ah at 12 V or 20 Ah at 24 V. Use the voltage on your battery label.
480 Wh at 12 volts equals 40 Ah.
480 Wh at 12 V
Equivalent charge capacity at this voltage
480 ÷ 12 = 40 Ah
- mAh
- 40,000
- Ah
- 40
- Wh
- 480
- kWh
- 0.48
These values describe the same battery rating at 12 V. Results are rounded for display; reversing uses full precision.
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 labelsDifferent voltages? Compare watt-hours, not just mAh.
Understand the conversion
The same energy can have different Ah ratings
Watt-hours account for both charge capacity and voltage. Amp-hours describe charge capacity at the stated voltage. When a battery lists Wh and your planning notes use Ah, divide its Wh rating by its nominal voltage.
A 12 V system name may be less specific than the battery label. If the label says 12.8 V, use 12.8: 480 Wh ÷ 12.8 V is 37.5 Ah. Using 12 V would give 40 Ah.
Formula and worked example
Ah = Wh ÷ V
Wh = Ah × V
480 Wh ÷ 12 V = 40 Ah. Reversing it gives 40 Ah × 12 V = 480 Wh.
Unit reference: NIST conversion factors lists ampere-hours under electric charge and watt-hours under energy. The battery calculations here use nominal label voltage.
480 Wh converted to Ah by voltage
The stored-energy rating stays at 480 Wh in each row. This reference table stays fixed while you edit the calculator.
| Wh | Nominal voltage | Ah |
|---|---|---|
| 480 | 3.7 V | 129.73 |
| 480 | 12 V | 40 |
| 480 | 12.8 V | 37.5 |
| 480 | 24 V | 20 |
| 480 | 25.6 V | 18.75 |
| 480 | 48 V | 10 |
| 480 | 51.2 V | 9.375 |
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 Ah is 1 kWh?
One kWh is 1,000 Wh. That is about 83.333 Ah at 12 V, 41.667 Ah at 24 V, or 20.833 Ah at 48 V. Select kWh in the calculator to enter it directly.
Will two batteries with the same Wh run a device for the same time?
Their nominal energy matches, but runtime can differ with voltage conversion, current limits, temperature, and usable discharge capacity. The battery must also meet the device's voltage and current requirements.