Convert Coulombs to Ampere-Hours
Coulomb (C) to Ampere-Hour (A·h) charge conversion — enter any value below to get an instant result, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1 C = 0.00027777778 A·h
1 Coulomb = 0.00027777778 Ampere-Hours
1 Ampere-Hour = 3600 Coulombs
1 C in every supported unit
Conversion chart: Coulomb to Ampere-Hours
Conversion table
| Coulomb (C) | Ampere-Hour (A·h) |
|---|---|
| 0.01 C | 2.77778E-06 A·h |
| 0.1 C | 2.77778E-05 A·h |
| 1 C | 0.00027777778 A·h |
| 2 C | 0.00055555556 A·h |
| 3 C | 0.00083333333 A·h |
| 5 C | 0.0013888889 A·h |
| 10 C | 0.0027777778 A·h |
| 20 C | 0.0055555556 A·h |
| 50 C | 0.013888889 A·h |
| 100 C | 0.027777778 A·h |
| 1000 C | 0.27777778 A·h |
Coulomb (C)
Definition: The SI derived unit of electric charge, defined as the charge carried by a steady current of one ampere flowing for one second. Since the 2019 redefinition of the SI, the coulomb is fixed exactly in terms of the elementary charge (the ampere is now defined so that the elementary charge equals precisely 1.602176634×10⁻¹⁹ C).
History: Named after French physicist Charles-Augustin de Coulomb, whose 1785 torsion-balance experiments established Coulomb's law describing the force between electric charges — the unit was adopted to honor that foundational contribution to electrostatics.
Current use: The universal reference unit for charge across electrical engineering, physics, and chemistry — every other unit on this page, historical or modern, is ultimately defined relative to it.
Ampere-Hour (A·h)
Definition: The charge transported by a steady current of one ampere flowing continuously for one hour, equal to 3,600 coulombs — a practical unit sized to match how batteries are actually specified and discharged.
History: It emerged naturally once battery capacity needed a convenient rating unit: since discharge current is normally quoted in amps and discharge duration in hours, multiplying the two gave engineers and consumers an intuitive capacity figure without needing to think in raw coulombs.
Current use: The standard unit for battery capacity ratings worldwide — printed directly on car batteries, and used (often as milliamp-hours) on phone, laptop, and EV battery specifications.
Supported Units
| Unit | Symbol | In Coulomb |
|---|---|---|
| Megacoulomb | MC | 1000000 C |
| Kilocoulomb | kC | 1000 C |
| Coulomb | C | 1 C |
| Millicoulomb | mC | 0.001 C |
| Microcoulomb | µC | 1E-06 C |
| Nanocoulomb | nC | 1E-09 C |
| Picocoulomb | pC | 1E-12 C |
| Abcoulomb | abC | 10 C |
| EMU of Charge | EMU | 10 C |
| Statcoulomb | statC | 3.33564E-10 C |
| ESU of Charge | ESU | 3.33564E-10 C |
| Franklin | Fr | 3.33564E-10 C |
| Ampere-Hour | A·h | 3600 C |
| Ampere-Minute | A·min | 60 C |
| Ampere-Second | A·s | 1 C |
| Faraday | F | 96485.309 C |
| Elementary Charge | e | 1.60218E-19 C |
About These Parameters
- Value
- The amount of electric charge you want to convert, expressed in the "From" unit. Accepts decimals, and can represent anything from a single elementary charge to a battery's full ampere-hour rating.
- From Unit
- The unit your input value is currently measured in — a battery datasheet's ampere-hour rating, an electrochemistry problem's faradays, or an older physics text's abcoulomb or statcoulomb figure.
- To Unit
- The unit you want the result converted into. Use the swap button to flip From and To instantly, which is handy when translating a historical CGS-system figure into the modern SI coulomb or vice versa.
How Charge Conversion Works
The Formula
Every unit here is defined by a fixed multiplier relative to the coulomb. To convert a value from one unit to another:
result = value × (factor of "From" unit ÷ factor of "To" unit)
For Coulomb → Ampere-Hour: multiply by 0.00027777778. For example, 1 C × 0.00027777778 = 0.00027777778 A·h.
From CGS Charge Units to the SI Coulomb
Before the SI system unified electricity around the ampere and coulomb, 19th-century physicists working in the centimeter-gram-second (CGS) system built two competing "natural" families of electrical units: the electrostatic (ESU) family, whose charge unit is the statcoulomb (also called the franklin, honoring Benjamin Franklin), defined so that two one-statcoulomb charges one centimeter apart repel with exactly one dyne of force; and the electromagnetic (EMU) family, whose charge unit is the abcoulomb, equal to a much larger 10 coulombs. Both systems made Maxwell's equations take a cleaner mathematical form than SI does, which is why some theoretical-physics and plasma-physics literature still uses Gaussian (CGS) units today — this converter lets you move any of those historical figures straight into the modern coulomb.
Why Batteries, Chemistry, and Physics Each Use a Different Unit
Battery engineers rate capacity in ampere-hours because that's literally how a battery is specified and discharged — a steady current for a certain duration. Electrochemists use the faraday because Faraday's laws of electrolysis relate charge passed directly to moles of substance deposited or liberated at an electrode, so working in "moles of charge" (faradays) keeps the chemistry intuitive. Particle physicists use the elementary charge because it's the smallest indivisible unit of free charge in nature, making it the natural yardstick for counting electrons, protons, or ionization events one at a time. All three units describe exactly the same physical quantity — they just scale it to whatever a given field actually measures day to day.
Example
A charge of 1 C equals 0.00027777778 A·h. For scale, a typical smartphone battery stores roughly 3,000-5,000 milliampere-hours (around 10,000-18,000 coulombs), a car battery is rated around 50-100 ampere-hours (180,000-360,000 coulombs), and a single lightning strike transfers on the order of 15-30 coulombs to the ground in well under a second.
Frequently Asked Questions
How many Ampere-Hours are in 1 Coulomb?
1 Coulomb (C) equals exactly 0.00027777778 Ampere-Hours (A·h).
What's the difference between a coulomb and an ampere-hour?
Both measure electric charge, but on very different scales. A coulomb is the charge moved by one ampere in one second; an ampere-hour is the charge moved by one ampere over a full hour, which is 3,600 times larger. Batteries are rated in ampere-hours (or milliampere-hours) because that matches how they're actually discharged, while raw coulombs are more common in circuit-level physics calculations.
Why are abcoulomb and EMU of charge the same value?
"EMU of charge" is simply the generic name for the CGS electromagnetic system's charge unit, and "abcoulomb" is that same unit's specific name — they're not two different quantities, just two names for one unit, both equal to 10 coulombs. The same relationship holds for statcoulomb, ESU of charge, and franklin, which are three names for the same CGS electrostatic charge unit.
How is the faraday related to the elementary charge?
The faraday is the charge of one full mole of elementary charges — multiply Avogadro's number (about 6.022×10²³) by the elementary charge (about 1.602×10⁻¹⁹ coulomb) and you get the Faraday constant, roughly 96,485 coulombs per mole. It's the bridge electrochemists use between "how many electrons were transferred" and "how much charge passed through the circuit."
Is the elementary charge the smallest possible amount of charge?
For any freely existing particle, yes — every electron and proton carries exactly one elementary charge (with opposite sign), and no isolated particle has ever been observed with a smaller fraction of it. Quarks carry fractional charges of ±1/3 or ±2/3 of the elementary charge, but they're never observed in isolation, only bound inside composite particles whose overall charge is always a whole multiple of the elementary charge.