Amperage calculator

Use this calculator to determine electric current in amps (A).

How to use it

  1. Select current type (Direct Current, AC - Single Phase, or AC - Three Phase)
  2. Enter power in watts
  3. Enter voltage in volts
  4. (For AC systems) Enter power factor
  5. (For AC - Three Phase only) Enter voltage type: Line to Line, or Line to Neutral
  6. Click on CALCULATE

Converting Watts to Amps (Direct Current system)

Calculating current I in amps (A) can be done by dividing the power P in watts (W) by voltage V in volts (V):

Equation

Converting Watts to Amps (AC single phase system)

Determine the phase current I in amps (A) by dividing power P in watts (W) by the power factor PF multiplied by the RMS voltage V in volts (V):

Equation

(The power factor is the ratio of the real power flowing to the load to the apparent power in the circuit. Power factor values can range from 0 to 1.

The RMS voltage is the square root of the mean over one cycle of the square of the instantaneous voltage.)

Converting Watts to Amps (AC three phase system)

Line to Line Voltage:

Calculate the phase current I in amps (A) by dividing the power P in watts (W) by the square root of 3 times the power factor PF times the line to line RMS voltage VL-L in volts (V):

Equation

(The power factor is the ratio of the real power flowing to the load to the apparent power in the circuit. Power factor values can range from 0 to 1.

Line to line voltage is the voltage measured between any two lines in a three phase circuit.)


Line to Neutral Voltage:

Determine the phase current I in amps (A) by dividing the power P in watts (W) by 3 times the power factor PF times the line to neutral RMS voltage VL-N in volts (V):

Equation

(The power factor is the ratio of the real power flowing to the load to the apparent power in the circuit. Power factor values can range from 0 to 1.

Line to neutral voltage is the voltage measured between any line and the neutral point.)