Electric Charge Converter
Same value in every unit
| Unit | Value |
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mAh is not how much energy a battery holds
This is the single most useful thing on this page. Milliampere-hours measure charge, and charge only becomes energy when multiplied by voltage. Two batteries with the same mAh rating at different voltages hold different amounts of energy.
Watt-hours = mAh × volts ÷ 1000. A 5000 mAh phone cell at 3.7 V is about 18.5 Wh. A 5000 mAh laptop pack at 11.1 V is about 55.5 Wh — three times as much, from the same headline number. Airlines limit cabin batteries in watt-hours for exactly this reason.
Reference points
- 5000 mAh — a large phone battery, 18,000 C
- 10,000 mAh — a typical power bank
- 60 Ah — a car battery, 216,000 C
- 1.6 × 10⁻¹⁹ C — a single proton
Where the faraday comes in
The Faraday constant, about 96,485 coulombs, is the charge carried by one mole of electrons. It is the bridge between electrical measurement and chemistry — how much metal an electroplating current will actually deposit.
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Frequently Asked Questions
5000 mAh is 18,000 coulombs of charge — but charge alone is not energy. To compare batteries you need watt-hours: multiply the mAh by the cell voltage and divide by 1000. A 5000 mAh phone cell at 3.7 V holds about 18.5 Wh.
Because they run at different voltages. A 5000 mAh power bank at 3.7 V and a 5000 mAh laptop battery at 11.1 V hold very different amounts of energy — three times apart. The mAh figure is only comparable within the same voltage.
One ampere flowing for one hour, which is 3600 coulombs. It is the practical unit for batteries because it maps directly onto how long a device will run at a known draw.
The charge on a single proton, exactly 1.602176634 × 10⁻¹⁹ coulombs since the 2019 redefinition of the SI units. It is a defined constant now, not a measurement.
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