Battery Life Calculator
Estimate how long a battery will last based on its capacity in mAh and the device power consumption in mA.
Estimated Battery Life
Battery Life Formula:
Hours = Battery Capacity (mAh) / Device Consumption (mA)
Example: A 3000 mAh battery powering a device that draws 150 mA:
3000 / 150 = 20 hours
Common battery capacities:
- AAA: 800–1200 mAh
- AA: 1800–3000 mAh
- 9V: 500–600 mAh
- 18650 Li-ion: 2000–3500 mAh
- Phone battery: 3000–5000 mAh
- Power bank: 5000–20000 mAh
Note: Real-world battery life is typically 70–80% of the theoretical value due to voltage regulation losses, temperature, and battery age. The calculator shows both ideal and realistic estimates.