How to use this tool
Enter each battery's mAh and cell voltage; check the power bank's output power and connector too.
Enter your details
All defaults are editable planning assumptions. Use actual product specifications and site conditions where possible.
How the estimate works
Convert the power bank and device battery from mAh and their respective cell voltages to Wh. Multiply bank Wh by delivered-energy fraction, then divide by device Wh.
Where product limits or site conditions matter, confirm them against the exact model and installation before buying.
Understanding your result
The charge count is an estimate after conversion losses. It is normal to receive fewer full charges than a simple mAh-to-mAh comparison suggests, especially when charging at high power or in cold conditions.
Choosing the right equipment
Compare rated watt-hours and USB-C output watts with the device you intend to charge. Check connector support and the power bank’s label; airline carriage requirements should be checked with your carrier before travel.