Electric Charge ConverterFree online other calculator — instant results, no sign-up
Convert standard electric charge units.
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About the Electric Charge Converter
The Electric Charge Converter converts electric charge between coulombs, ampere-hours, and milliampere-hours. It uses fixed unit relationships to express the same charge in your selected unit. With the default settings, 1 coulomb converts to 0.277778 milliampere-hour.
- Value
- The electric charge to convert, expressed in the selected From unit; the default is 1.
- From
- The unit of the entered charge—coulomb (C), ampere-hour (Ah), or milliampere-hour (mAh)—with coulomb selected by default.
- To
- The desired output unit—milliampere-hour (mAh), ampere-hour (Ah), or coulomb (C)—with milliampere-hour selected by default.
Formula and method
Q_out = Q_in × (k_from / k_to), where k(C) = 1, k(Ah) = 3600, and k(mAh) = 3.6, each expressed in coulombs per unit. For the default inputs: Q_out = 1 × (1 / 3.6) = 0.277777… mAh ≈ 0.277778 milliampere-hour.
- Q_inThe numerical charge value entered in the From unit.
- Q_outThe numerical charge value expressed in the To unit.
- k_fromThe number of coulombs in one unit of the selected From unit.
- k_toThe number of coulombs in one unit of the selected To unit.
- k(u)The conversion factor in coulombs per unit for charge unit u.
The calculator first multiplies the entered value by the source unit's coulomb factor, then divides by the target unit's coulomb factor. These factors follow from 1 C = 1 A·s, 1 Ah = 3600 C, and 1 mAh = 3.6 C. For the default conversion, dividing 1 coulomb by 3.6 coulombs per milliampere-hour gives the displayed result of 0.277778 milliampere-hour.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Value1
- Fromcoulomb
- Tomilliampere-hour
Results
- Result0.277778 milliampere-hour
How to use the Electric Charge Converter
- 1Enter the charge in Value; leave it at 1 to follow the default example.
- 2Choose the starting unit in From; use coulomb for the default example.
- 3Choose the desired unit in To; use milliampere-hour for the default example.
- 4Read the converted Result: with the default inputs, it is 0.277778 milliampere-hour.
Reading your result
The Result row shows the entered charge expressed in the To unit, not an additional quantity of charge. In the default example, 0.277778 milliampere-hour represents the same charge as 1 coulomb, rounded to six decimal places.
Limitations
This tool converts only coulombs, ampere-hours, and milliampere-hours using exact unit factors; the displayed result may be rounded. It does not convert charge directly into energy, voltage, or current. Battery capacity expressed in Ah or mAh is a charge rating, and converting it does not account for battery aging, temperature, discharge conditions, or usable energy. The conversion also does not improve the accuracy of the original measurement.
Common questions
Why does 1 coulomb become 0.277778 milliampere-hour?+
One milliampere-hour equals 3.6 coulombs, so the calculator divides 1 by 3.6. The result is 0.277777… milliampere-hour, displayed as 0.277778.
Are ampere-hours and milliampere-hours units of current?+
No. Amperes and milliamperes measure current, while ampere-hours and milliampere-hours measure charge: current multiplied by time. One ampere-hour equals 1000 milliampere-hours.
Can this converter turn a battery's milliampere-hour rating into watt-hours?+
No. Watt-hours measure energy rather than charge. Estimating battery energy requires voltage as well: energy in Wh is approximately charge in Ah multiplied by nominal voltage in V.
What happens if From and To are the same charge unit?+
The conversion factor is 1, so the charge value remains unchanged apart from any display formatting or rounding.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
Further reading
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Results are estimates for informational purposes and are not financial, medical or legal advice.