Battery Life Calculator
How to estimate battery life
- Enter the battery capacity in mAh.
- Enter the current your device draws when active, the share of time it is active and its sleep current.
- Keep 85% usable capacity or change it to see the running time.
Frequently asked questions
Why not use the full capacity?
Batteries rarely deliver their full rating in practice: the capacity drops with high current, cold and age, and devices stop before the battery is completely empty.
How is the running time worked out?
The usable capacity divided by the average current. The average is the active current times the share of time active, plus the sleep current for the rest.
How do I find my device's current?
Measure it with a multimeter in series with the battery, or take it from the datasheets of the main parts.