An easy to use power calculator tool that can calculate a battery's use time (in hours), a needed battery rating (in milliamp-hours or amp-hours), or the average draw of power (in amps or milliamps) in a given setup.

If you want to calculate the hours of use for a battery, plug in the battery rating number and the average draw of the devices connected.

If you want to calculate what kind of battery capacity you need to run a certain device for a certain amount of time, plug in the average draw and time requirement.

If you want to know much drain a specific battery can take for a specific amount of time, plug in the amount of time and battery rating and you get the average power you can use for that amount of time.

Use the battery efficiency slider to get better calculations based on the type and age of the battery.

The calculations produced by this app are estimations only and shouldn't be considered 100% accurate. Use conservative battery efficiency values to make better estimates.