Electric current is the flow of charge — measured in amperes. Understanding current is essential for choosing wire sizes and fuse ratings.
What Is Current?
Current (I) is the rate of charge flow. 1 ampere = 1 coulomb per second. Like water flow: current is flow rate, voltage is pressure.
Current Units
- 1 A = 1,000 mA
- 1 mA = 1,000 µA
USB 2.0: 500 mA. USB 3.0: 900 mA. Phone charger: 1–3 A.
Typical Values
LED: 5–20 mA. Arduino pin: max 40 mA. Car headlight: 5–15 A. Circuit breaker: 15–20 A. Lightning: ~30,000 A.
Try the Electric Current Converter
Convert between all electric current units instantly.
Frequently Asked Questions
What is the difference between amps and milliamps?
1 A = 1,000 mA. Milliamps for small currents (electronics); amps for larger currents (appliances).