Ampere to Milliampere Converter
Quickly convert from Ampere to Milliampere.
How to convert
Formula:
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Electric current conversion is foundational in electronics and electrical engineering.
Where is it used?
• Consumer Electronics — Smartphone charging: 1-5 A; USB-A standard: 500 mA; USB-C PD: up to 5 A (100 W at 20 V).
Examples:
• 1 A = 1,000 mA
• 1 mA = 1,000 μA
Electric current conversion is foundational in electronics and electrical engineering. Amperes, milliamperes, and microamperes measure the flow of electric charge — from the 0.1 mA that triggers a digital input to the 400 A of a welding machine.
Electric current is the rate of flow of electric charge. The SI base unit is the ampere (A), defined since 2019 as an exact number of elementary charges per second (1 A = 6.241509 × 10¹⁸ electrons/second). Milliampere (mA) = 0.001 A; microampere (μA) = 10⁻⁶ A; kiloampere (kA) = 1,000 A.
Where is it used?
- Consumer Electronics — Smartphone charging: 1-5 A; USB-A standard: 500 mA; USB-C PD: up to 5 A (100 W at 20 V).
- Household Circuits — Standard outlet circuits: 15-20 A (US), 16 A (EU); electric stoves and dryers: 30-50 A.
- Automotive — Starter motor: 200-600 A during cranking; car audio systems: 20-100 A; EV charging: 16-250 A.
- Medical Devices — TENS therapy: 1-80 mA; safe ECG signal measurement: microamperes; lethal threshold: ~100 mA through the heart.
- Industrial — Arc welding: 50-500 A; large motors: 100-2,000 A; aluminum smelting electrolysis: 150,000-500,000 A.
Common Conversion Mistakes
Confusing current with voltage
Current (A) is the flow of charge; voltage (V) is the electrical pressure. Both are needed to calculate power: P = V × I. A 1 A current at 5 V uses 5 W; the same 1 A at 120 V uses 120 W.
Neglecting fuse ratings
Fuses protect against overcurrent. A 20 A fuse allows up to 20 A continuously. Loading a circuit to its fuse limit continuously causes heat buildup. The NEC recommends loading circuits to no more than 80% of rated capacity continuously.
Underestimating danger of current
Current — not voltage — kills. 1 mA: barely perceptible. 10 mA: painful, may cause loss of muscle control. 100 mA through the heart for even 1 second can cause fatal ventricular fibrillation. High voltage is dangerous because it can drive lethal current through body resistance.
Ignoring inrush current
Motors, transformers, and capacitive power supplies draw much more current at startup than during normal operation. Inrush current can be 5-10× the running current. Circuit breakers and fuses must be rated for inrush, not just steady-state.
Quick Reference Table
| From | To |
|---|---|
| 1 A | 1,000 mA |
| 1 mA | 1,000 μA |
| USB-A port | 500 mA max |
| Household circuit (US) | 15-20 A |
| Car starter motor | 200-600 A |
| Lightning strike | 30,000 A peak |
| EV fast charger | up to 250 A |
| AA battery (short circuit) | ~5-10 A |
Frequently Asked Questions
How dangerous is 1 mA?
Effects depend on path through the body and duration. 1 mA: just perceptible tingle. 5-10 mA: painful. 10-20 mA: cannot let go (muscle seizure). 50-100 mA: ventricular fibrillation risk. 100 mA: almost certainly fatal if through the heart. High-voltage environments are deadly because they can force these currents through typical body resistance.
How does current relate to charging speed?
Charging power = voltage × current. A USB-A charger (5 V, 1 A) delivers 5 W. A USB-C PD charger (20 V, 5 A) delivers 100 W — 20× faster. Modern fast-charging standards use higher voltages to reduce current (and heat in cables) while increasing power.
What is alternating current (AC)?
In AC, current reverses direction periodically — 50 times per second at 50 Hz, or 60 times at 60 Hz. Mains power is AC because transformers can change voltage levels efficiently, enabling long-distance transmission at high voltage (low current, less loss) and distribution at safe voltages.
What is the ampere officially defined as?
Since the 2019 SI redefinition, the ampere is defined by fixing the elementary charge (e = 1.602176634 × 10⁻¹⁹ C). One ampere = exactly 1/1.602176634 × 10⁻¹⁹ elementary charges per second ≈ 6.241509 × 10¹⁸ electrons per second.
Sources & Standards
- International Bureau of Weights and Measures (BIPM) — SI Brochure 9th edition
- International Electrotechnical Commission (IEC)
- Institute of Electrical and Electronics Engineers (IEEE)
Reviewed by The Unit Hub Editorial Team · March 2026