About the Electrical Charge Converter
Electric charge is measured in coulombs, but batteries are labelled in amp-hours and milliamp-hours because that is what matters when you are deciding how long something will run.
How it works
Charge is current multiplied by time: 1 coulomb = 1 amp for 1 second, so 1 amp-hour = 3,600 coulombs.
| Unit | In coulombs |
|---|---|
| 1 millicoulomb (mC) | 0.001 C |
| 1 microcoulomb (µC) | 0.000001 C |
| 1 milliamp-hour (mAh) | 3.6 C |
| 1 amp-hour (Ah) | 3,600 C |
- Pick the units.
- Enter the value.
- Read the converted charge.
Examples
Worked examples:
- A 5,000 mAh power bank holds 5,000 × 3.6 = 18,000 coulombs, and can supply 500 mA for about 10 hours before losses.
- A 60 Ah car battery holds 216,000 coulombs.
- A 3,000 mAh phone battery drawing 300 mA lasts roughly 10 hours.
Real runtimes are 10–25% lower than the arithmetic suggests, because converting voltage loses energy as heat. For the voltage and current side of the same circuit, use the Ohm's law calculator.
Electrical Charge Converter: frequently asked questions
- How do I convert mAh to coulombs?
Multiply by 3.6. A 3,000 mAh battery holds 10,800 coulombs.
- Does a higher mAh mean a longer battery life?
Only at the same voltage and draw. A 5,000 mAh power bank at 3.7 V holds less energy than a 4,000 mAh battery at 7.4 V — compare watt-hours for a fair answer.
- Why does a 10,000 mAh power bank not fully charge a 3,000 mAh phone three times?
Because the voltage has to be stepped up and back down, which wastes 10–25% as heat. Two and a half charges is a realistic result.