Coulomb to Millicoulomb Converter
Quickly convert from Coulomb to Millicoulomb.
How to convert
Formula:
—
Electric charge conversion connects fundamental physics to everyday electronics.
Where is it used?
• Battery Capacity — Smartphone batteries: 3,000-6,000 mAh; EV batteries: 60-200 Ah (at pack voltage); AA alkaline battery: ~2,500-3,000 mAh.
Examples:
• 1 Ah = 3,600 C
• 1 mAh = 3.6 C
Electric charge conversion connects fundamental physics to everyday electronics. Coulombs, milliampere-hours, and ampere-hours all measure the quantity of electricity — from the charge in a single electron to the capacity of an EV battery pack.
Electric charge is the fundamental property of matter responsible for electromagnetic interactions. The SI unit is the coulomb (C), defined since 2019 as exactly 6.241509074 × 10¹⁸ elementary charges. In practical electronics, charge is often expressed as ampere-hours (Ah) or milliampere-hours (mAh): 1 Ah = 3,600 C.
Where is it used?
- Battery Capacity — Smartphone batteries: 3,000-6,000 mAh; EV batteries: 60-200 Ah (at pack voltage); AA alkaline battery: ~2,500-3,000 mAh.
- Electrochemistry — Faraday's law: 96,485 C deposits 1 mole of a monovalent ion. Used in electroplating thickness calculations.
- Capacitors — Q = C × V. A 1,000 μF capacitor charged to 10 V stores 0.01 C (10 mC).
- Particle Physics — Elementary charge e = 1.602 × 10⁻¹⁹ C is the charge of one proton or electron.
- EV Charging — A 22 kW charger at 400 V delivers 55 A = 55 C/s. Charging a 100 Ah battery from empty takes about 4.5 hours at 22 A.
Common Conversion Mistakes
Confusing charge (Ah) with energy (Wh)
A 100 Ah battery at 12 V stores 1,200 Wh (1.2 kWh). A 100 Ah EV battery at 400 V stores 40,000 Wh (40 kWh). Same amp-hours, but 33× more energy because of the higher voltage. Always multiply Ah × V to get watt-hours.
Assuming mAh is directly comparable across different voltages
A 3,000 mAh phone battery at 3.7 V holds 11.1 Wh. A 3,000 mAh laptop battery at 11.1 V holds 33.3 Wh — 3× more energy. For comparing batteries at different voltages, always convert to watt-hours.
Forgetting that rated capacity is at a specific discharge rate
Battery capacity decreases at higher discharge rates. A 100 Ah battery may only deliver 80 Ah when discharged quickly (high C-rate). Manufacturers often rate at C/20 (discharge over 20 hours) — real-world capacity may be less.
Mixing up coulombs in formulas
Current (A) = charge (C) / time (s). So 1 A flowing for 1 hour = 3,600 C = 1 Ah. When using Faraday's law or capacitor equations, charge must be in coulombs (not Ah or mAh).
Quick Reference Table
| From | To |
|---|---|
| 1 Ah | 3,600 C |
| 1 mAh | 3.6 C |
| 1 C | 1 A·s |
| 1 elementary charge (e) | 1.602 × 10⁻¹⁹ C |
| 1 Faraday | 96,485 C/mol |
| AA battery | ~2,500-3,000 mAh |
| Smartphone battery | 3,000-6,000 mAh |
| EV battery (75 kWh @ 400 V) | 187.5 Ah |
Frequently Asked Questions
What does mAh mean for batteries?
Milliampere-hour: a battery rated at 3,000 mAh can deliver 3,000 mA (3 A) for 1 hour, or 300 mA for 10 hours, or 1,500 mA for 2 hours before exhaustion. It's a measure of total charge stored — how long a battery lasts depends on how much current the device draws.
How do I convert mAh to watt-hours (Wh)?
Wh = mAh × V / 1,000. Example: a 4,000 mAh phone battery at 3.8 V nominal = 4,000 × 3.8 / 1,000 = 15.2 Wh. This lets you compare batteries at different voltages fairly.
How much charge does lightning contain?
A typical lightning bolt transfers about 5 coulombs of charge over about 0.2 seconds, with a peak current of about 30,000 A. The energy is roughly 1-5 GJ (gigajoules), but it's concentrated in microsecond pulses, making it nearly impossible to capture practically.
What is the Faraday constant?
The Faraday constant (F ≈ 96,485 C/mol) is the charge of one mole of electrons. It relates to electrochemistry: to deposit 1 mole of copper (63.5 g) from solution requires 2 × 96,485 = 192,970 C (because copper ions are Cu²⁺). Essential for calculating electroplating thickness and electrolysis yields.
Sources & Standards
- International Bureau of Weights and Measures (BIPM) — SI Brochure 9th edition
- International Electrotechnical Commission (IEC)
- National Institute of Standards and Technology (NIST)
Reviewed by The Unit Hub Editorial Team · March 2026