Battery Life Calculator
Runtime from battery energy and average power draw, with an uncertainty range.
How it’s calculated
Runtime (h) = usable energy (Wh) ÷ average power (W). Usable energy = capacity × health.
Limitations & assumptions
Real draw changes with brightness, workload and temperature. Phones list mAh: Wh = mAh × voltage ÷ 1000.
FAQ
Where do I find my draw?
OS battery reports or a USB power meter give real numbers.