How this conversion works
The ampere is the SI base unit of electric current. Metric units differ by powers of ten: 1 A = 1,000 mA = 1,000,000 µA.
The CGS abampere equals 10 A exactly; the statampere is about 3.3356 × 10⁻¹⁰ A.
Current is the rate at which charge flows: one ampere is one coulomb passing a point each second. Small electronics are usually rated in milliamps, while household circuits and chargers are rated in amps.
Converting units never changes the physical current. A device drawing 0.25 A draws exactly 250 mA; only the number and the unit label change.
Formula: result = value × (base units per source unit) ÷ (base units per target unit)
Where this conversion is used
- Reading multimeter values in mA or µA.
- Device current draw and battery life estimates.
- Electrical component ratings such as fuses and LEDs.
Worked example: 250 mA in amperes
- 1 mA = 0.001 A.
- 250 × 0.001 = 0.25 A.
Unit definitions
| Unit | In amperes | Note |
|---|---|---|
| Ampere (A) | 1 | |
| Kiloampere (kA) | 1,000 | |
| Milliampere (mA) | 0.001 | |
| Microampere (µA) | 0.000001 | |
| Nanoampere (nA) | 1e-9 | |
| Abampere (biot) (abA) | 10 | |
| Statampere (statA) | 3.33564e-10 |
Milliamperes to amperes
| Milliampere (mA) | Ampere (A) |
|---|---|
| 1 | 0.001 |
| 10 | 0.01 |
| 100 | 0.1 |
| 250 | 0.25 |
| 500 | 0.5 |
| 1,000 | 1 |
| 2,000 | 2 |
Microamperes to milliamperes
| Microampere (µA) | Milliampere (mA) |
|---|---|
| 1 | 0.001 |
| 10 | 0.01 |
| 100 | 0.1 |
| 500 | 0.5 |
| 1,000 | 1 |
Things to watch for
- Battery capacity in mAh is charge, not current. Use the Electric Charge Converter for mAh, Ah and coulombs.
Precision and sources
Results are calculated from the definitions above and rounded to 12 significant digits; the converter shows up to eight decimal places and the tables four. Reference: BIPM, The International System of Units (SI Brochure), 9th edition (2019).
Frequently asked questions
How many milliamps are in an amp?
1,000. To turn milliamps into amps, divide by 1,000; to turn amps into milliamps, multiply by 1,000.
Is 500 mA the same as 0.5 A?
Yes. 500 ÷ 1,000 = 0.5 A. USB 2.0 ports, for example, are specified at 500 mA, which is the same as 0.5 A.
Does this tell me if a wire or fuse is safe?
No. It only changes units. Safe wire sizes and fuse ratings depend on local electrical codes and the manufacturer's specifications.