Use Ohm’s law: Amps = Volts ÷ Ohms
Measure voltage with a multimeter
Measure resistance with a multimeter
Divide voltage by resistance to get current
Use a clamp meter to measure current directly
Check the device label for rated current
Use power formula: Amps = Watts ÷ Volts
For AC circuits, use a true RMS meter if needed
For three-phase systems, use the appropriate three-phase current formula
Verify the circuit is de-energized before measuring resistance
Match the meter setting to AC or DC current before measuring