Convert Coulombs to Ampere-hours
Convert Coulombs (C) to Ampere-hours (Ah) instantly and accurately.
Conversion Formula
Ah = C × 0.0002777777778
About Coulombs
The coulomb (C) is the SI derived unit of electric charge, equal to the charge transported by a current of 1 A in 1 s. In the 2019 SI revision it is fixed exactly via the elementary charge: 1 C = 1 / (1.602 176 634 × 10⁻¹⁹) e ≈ 6.241 × 10¹⁸ e. Practical benchmarks: a 1 Ah battery stores 3 600 C; a lightning bolt transfers 1-20 C.
About Ampere-hours
The ampere-hour (Ah) equals exactly 3 600 C and is the universal capacity unit for rechargeable batteries. Lead-acid car batteries are rated 40-100 Ah; EV traction packs use 50-300 Ah cells; industrial forklift batteries exceed 1 000 Ah. Multiplying Ah by nominal voltage gives watt-hours of stored energy. 1 Ah = 3 600 C = 1 000 mAh.
Quick Reference Table
| Coulombs (C) | Ampere-hours (Ah) |
|---|---|
| 1 C | 0.000277778 Ah |
| 2 C | 0.000555556 Ah |
| 5 C | 0.00138889 Ah |
| 10 C | 0.00277778 Ah |
| 25 C | 0.00694444 Ah |
| 50 C | 0.0138889 Ah |
| 100 C | 0.0277778 Ah |