Enter the Wh (watt-hours) and the voltage (volts) into the Calculator. The calculator will evaluate the mAh from Wh.
- All Unit Converters
- Amp Hour to Watt Hour (ah ↔ wh) Calculator
- Battery Capacity Calculator (Amp Hours)
mAh from Wh Formula
mAh = Wh*1000 / V
Variables:
- mAh is the capacity in milliampere-hours (mAh)
- Wh is the energy in watt-hours (Wh)
- V is the voltage (volts)
To calculate mAh from Wh, multiply the watt-hours by 1000, then divide by the voltage.
| Watt-hours (Wh) | Milliamp-hours (mAh) |
|---|---|
| 0.5 | 135.135 |
| 1 | 270.270 |
| 1.5 | 405.405 |
| 2 | 540.541 |
| 2.5 | 675.676 |
| 3 | 810.811 |
| 3.7 | 1000.000 |
| 5 | 1351.351 |
| 7.4 | 2000.000 |
| 10 | 2702.703 |
| 11.1 | 3000.000 |
| 12 | 3243.243 |
| 15 | 4054.054 |
| 18.5 | 5000.000 |
| 20 | 5405.405 |
| 24 | 6486.486 |
| 36 | 9729.730 |
| 50 | 13513.514 |
| 72 | 19459.459 |
| 100 | 27027.027 |
| * Rounded to 3 decimals. Assumes nominal voltage V = 3.7 V. Formula: mAh = (Wh × 1000) / V. At 3.7 V: 1 Wh ≈ 270.270 mAh. | |
How to Calculate mAh from Wh?
The following steps outline how to calculate the mAh from Wh.
- First, determine the Wh (watt-hours).
- Next, determine the voltage (volts).
- Next, gather the formula from above = mAh = Wh*1000 / V.
- Finally, calculate the mAh from Wh.
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
Wh (watt-hours) = 675
voltage (volts) = 40
mAh = (675 × 1000) / 40 = 16,875 mAh
FAQs
What is mAh and why is it important?
mAh stands for milliampere-hour and is a unit of electric charge (current × time). It’s commonly used to describe a battery’s charge capacity—how much current a battery can supply over time under specified conditions. Battery energy capacity is measured in watt-hours (Wh) and depends on voltage (Wh = Ah × V).
How does voltage affect battery life?
Voltage affects how charge capacity (mAh) relates to energy (Wh). For a fixed amount of energy in watt-hours, the equivalent mAh is inversely proportional to voltage: mAh = (Wh × 1000) / V, so a higher voltage corresponds to a lower mAh value for the same Wh. Actual runtime (“battery life”) depends mainly on the device’s power draw (W), operating conditions, and conversion efficiency.
Can you convert Wh to mAh for any battery type?
Yes—if you know the battery’s energy in watt-hours (Wh) and an appropriate voltage to use, you can convert to mAh using mAh = (Wh × 1000) / V. Because many batteries’ voltage changes during discharge, this conversion typically uses the battery’s nominal (average) voltage for an estimate.
Is it better to have a higher mAh rating?
A higher mAh rating means more charge capacity at the same voltage, which often translates to longer runtime. However, if you’re comparing batteries with different voltages, mAh alone can be misleading—compare watt-hours (Wh) to compare stored energy directly. The “best” capacity depends on your device’s power requirements, size/weight constraints, and how you use it.
