Charge Converter
Convert electric charge between coulombs and ampere-hours - handy for comparing battery capacities listed in mAh, Ah or coulombs.
About the Charge Converter
This tool converts electric charge between coulombs, millicoulombs, microcoulombs, ampere-hours and milliampere-hours. The coulomb is the SI unit of charge, while ampere-hours and milliampere-hours are the practical units printed on batteries and power banks.
How to use it
- Enter the value you have into its field, for example a power-bank rating in mAh.
- Read the equivalent in ampere-hours or coulombs.
- Convert in either direction to compare capacities given in different units.
The crucial link is between ampere-hours and coulombs: one ampere-hour equals 3600 coulombs, because an amp flowing for one hour (3600 seconds) moves that much charge. So a 2000 mAh cell holds 2 Ah, or 7200 coulombs. A common pitfall is comparing power banks by mAh alone - capacity in watt-hours (mAh times voltage) is the fairer comparison, since cells at different voltages store different energy for the same mAh. This converter only handles charge units, runs in your browser, and uploads nothing.
Frequently asked questions
How many coulombs are in an ampere-hour?
One ampere-hour equals 3600 coulombs, because one ampere flowing for one hour (3600 seconds) transfers 3600 coulombs of charge.
How do I convert mAh to coulombs?
Multiply milliampere-hours by 3.6. So a 1000 mAh battery holds 3600 coulombs, equal to 1 Ah.
Can I compare battery capacity using mAh alone?
Only if the batteries share the same voltage. mAh measures charge, not energy. To compare across voltages, convert to watt-hours by multiplying mAh by the cell voltage.
What is a coulomb?
A coulomb is the SI unit of electric charge, equal to the charge carried by a one-ampere current in one second. It corresponds to roughly 6.24 x 10^18 electrons.