Authoritative definitions of the International System of Units and SI prefixes.
Dedicated unit pair
Coulombs to Ampere-hours
Convert C to Ah instantly, then review the formula, assumptions, and rounding guidance.
Electrical unitsInstant result
Decimals
Formula result = input × 1 ÷ 3600. 1 C = 0.0003 Ah
Common examples
One value, several units
Millicoulombs1,000 mC
Microcoulombs1,000,000 µC
Ampere-hours0.0003 Ah
Milliampere-hours0.2778 mAh
Conversion table
| C | Ah |
|---|---|
| 1 C | 0.0003 Ah |
| 2 C | 0.0006 Ah |
| 5 C | 0.0014 Ah |
| 10 C | 0.0028 Ah |
| 25 C | 0.0069 Ah |
| 50 C | 0.0139 Ah |
| 100 C | 0.0278 Ah |
Conversion chart
1 C0.0003 Ah
5 C0.0014 Ah
10 C0.0028 Ah
25 C0.0069 Ah
50 C0.0139 Ah
Worked example
1 ampere-hour equals exactly 3,600 coulombs.
Unit definition
Coulombs (C) One coulombs equals 1 coulomb.
Unit history
Coulombs is represented here using its modern SI definition or an internationally accepted relationship to an SI base unit.
Step by step
1. Parse the value, including fractions.
2. Convert C to coulomb.
3. Convert the base value to Ah and apply your display precision.
Understand the result before using it
Coulombs to Ampere-hours converts a value measured in Coulombs (C) into the equivalent value in Ampere-hours (Ah). The numerical value changes because the size and definition of the selected unit changes; the underlying quantity does not.
Calculated result
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.
Formula, assumptions, and example
Formula
result = input × 1 ÷ 3600
Assumptions
- Coulombs and Ampere-hours represent the same electric charge quantity.
- The input is expressed in C; the output is expressed in Ah.
- The unit definitions and conventional relationship shown on this page apply.
Worked example
1 C = 0.000277777777778 Ah. For another value, apply the same relationship and round only to the precision your source measurement supports.
When to use it
Good uses
- Read a C measurement in a document that expects Ah.
- Compare a coulombs value with a value reported in ampere-hours.
- Check the C-to-Ah arithmetic before copying the result into another calculation.
Limitations
Common mistakes to avoid
- Do not confuse C with another unit that has a similar name or symbol.
- Round the output to a precision justified by the original measurement.
- Verify safety-critical, regulated, laboratory, and contractual conversions against the controlling standard.
Sources and further reading
These references explain the underlying standards or provide authoritative context. Your own contract, institution, clinician, product documentation, local code, or governing standard may be the controlling source.
Guidance on unit names, symbols, conversions, and numerical presentation.
Questions about this calculation
How do I convert Coulombs to Ampere-hours?
result = input × 1 ÷ 3600 Using the displayed relationship, 1 C equals 0.000277777777778 Ah.
How many Ampere-hours are in one Coulombs?
One Coulombs is 0.000277777777778 Ampere-hours. The displayed digits may be rounded.
Can I reverse the C to Ah conversion?
Yes. Swap the source and target units in the converter. The reverse relationship converts Ah back to C.
Is the Coulombs to Ampere-hours result exact?
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.