Coulombs to ampere-hours
Type a value in coulombs to see it in ampere-hours straight away, or type in the second box to convert back.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Type the value in the coulombs box.
- Read the result in ampere-hours as you type, and pick the precision you need.
- Swap the direction to convert back, or copy the result.
How it is calculated
Ah = C × 0.0002777777778
Multiply the value in coulombs by 0.0002777777778 to get ampere-hours.
Example
To convert 25 C to ampere-hours: 25 × 0.0002777777778 = 0.00694444 Ah.
Conversion table
| Coulombs (C) | Ampere-hours (Ah) |
|---|---|
| 1 | 0.000277778 |
| 2 | 0.000555556 |
| 3 | 0.000833333 |
| 5 | 0.00138889 |
| 10 | 0.00277778 |
| 20 | 0.00555556 |
| 25 | 0.00694444 |
| 50 | 0.0138889 |
| 100 | 0.0277778 |
| 250 | 0.0694444 |
| 500 | 0.138889 |
| 1,000 | 0.277778 |
About the units
- Coulomb
- The SI unit of charge: the charge carried by a current of one ampere in one second, so 1 C = 1 A·s.
- Ampere-hour
- The charge moved by one ampere flowing for one hour, exactly 3600 coulombs, used for car and solar battery capacity.
Limits and caveats
- Results are rounded for display and computed with the browser's floating point precision (about 15 significant digits).
- Both unit factors are exact by their official definitions.
Questions about this tool
How many ampere-hours are in one coulomb?
1 C = 0.000277778 Ah exactly.
How do I convert coulombs to ampere-hours?
Use Ah = C × 0.0002777777778. For example, 25 C = 0.00694444 Ah.
How many coulombs are in one ampere-hour?
1 Ah = 3,600 C.
How do I convert battery mAh to watt-hours?
You need the battery voltage: Wh equals mAh times volts divided by 1000. A 5000 mAh battery at 3.7 V holds 18.5 Wh.
How many coulombs are in an ampere-hour?
Exactly 3600 coulombs, because an ampere-hour is one ampere flowing for 3600 seconds.