Milliamp Hours Calculator: Convert mAh to Wh, Ah & Hours
Popular mAh queries
Wh results assume a 3.7V battery. Runtime results assume a steady 1,000mA load. Use the calculator below for the exact value at your voltage and load.
| Popular query | Result |
|---|---|
| 1mah to wh | 0.0037 Wh |
| 425mah to hours | 0.425 hours |
| 3000mah to ah | 3 Ah |
| 5000mah to ah | 5 Ah |
| 6000mah to ah | 6 Ah |
| 8000mah to ah | 8 Ah |
| 10000mah to ah | 10 Ah |
| 12000mah to ah | 12 Ah |
| 15000mah to ah | 15 Ah |
| 20000mah to ah | 20 Ah |
| 78800mah to hours | 78.8 hours |
Voltage changes the Wh result. A 10,000mAh battery is 37Wh at 3.7V, but 120Wh at 12V.
What does this battery really hold?
Enter capacity and voltage for Ah and Wh, then choose current draw or device power to estimate theoretical runtime.
How to use the milliamp hours calculator
- 1Enter capacity.
Use the mAh number printed on the battery, power bank or device datasheet.
- 2Add nominal voltage.
Voltage is required for Wh. Use the pack rating, not the full-charge voltage.
- 3Choose a runtime path.
Enter average current in mA or average power in W. The result updates immediately.
Milliamp hours calculator formulas
mAh measures charge. Voltage converts charge into energy, and a device's average load converts that capacity into hours.
For power-based runtime, use hours ≈ Wh ÷ average W. These are theoretical results; conversion efficiency, cutoff voltage, battery age, temperature and changing load affect reality.
How many hours is a given mAh battery?
You need the average load. A 425mAh battery lasts about 4.25 theoretical hours at 100mA, but only 0.85 hours at 500mA. Likewise, 78,800mAh is 78.8 hours at 1,000mA or 39.4 hours at 2,000mA. Halving the load roughly doubles runtime.
mAh vs Ah vs Wh
- mAh
- Charge capacity in milliamp-hours, common on phones, sensors and power banks.
- Ah
- The same charge measure at a larger scale: 1 Ah equals 1,000 mAh.
- Wh
- Stored energy. Wh lets you compare batteries only after voltage is included.
- W and runtime
- Watts describe the device load. Runtime is stored Wh divided by average W.
FAQ
Can you convert mAh directly to hours?
Not from mAh alone. Divide capacity in mAh by the device's average current draw in mA, or convert mAh to Wh with voltage and divide by average power in watts.
How many hours will a 425 mAh battery last?
At a constant 100 mA draw, 425 mAh is about 4.25 theoretical hours. At 500 mA it is about 0.85 hours. Real runtime is usually lower.
How many hours is 78,800 mAh?
It depends on load. At 1,000 mA, 78,800 mAh is about 78.8 theoretical hours; at 2,000 mA, it is about 39.4 hours.
How many watt-hours is 10,000 mAh at 3.7V?
10,000 mAh at 3.7V is 37 Wh: 10,000 × 3.7 ÷ 1,000 = 37. Voltage is required because mAh measures charge, not energy.
How many mAh are in 14 Ah?
14 Ah equals 14,000 mAh. Multiply amp-hours by 1,000 to convert Ah to mAh.
What voltage should I use for a power bank?
Use the nominal voltage stated for the cells or internal battery, commonly 3.7V. Do not use the 5V USB output unless the capacity is also rated at that output voltage.
Why is real battery runtime lower than the estimate?
Conversion losses, battery age, temperature, cutoff voltage and a changing load all reduce or change real runtime. Treat the result as a theoretical upper bound.