Battery runtime calculator

Estimate how long a battery can power a device at a steady load.

Numbers Stateless

Quick guide

Try an example

You enter

Battery capacity (Wh)
200
Steady load (W)
40
Usable capacity (%)
80

You get

4 h
How it works and limits

Use battery capacity in watt-hours and load in watts. Enter the usable percentage to account for a reserve or estimated losses.