Device tool

Power Bank Output Calculator

Convert a power bank's advertised cell capacity into estimated usable USB watt-hours and device charges at selectable efficiencies.

Estimate usable output

mAh
V
V
%
Wh
%

Ready when you areEnter known values and review the assumptions shown with the result.

This tool runs locally in your browser. Device access is requested only when needed and can be revoked through browser controls.