Enter the average power (watts) and the RMS voltage into the calculator to determine the RMS Current. 

RMS Current Formula

The following formula is used to calculate the RMS Current. 

Irms = Pave / Vrms

  • Where Irms is the RMS Current (amps)
  • Pave is the average power (watts) 
  • Vrms is the RMS voltage (volts)

How to Calculate RMS Current?

The following two example problems outline how to calculate the RMS Current.

Example Problem #1:

  1. First, determine the average power (watts). In this example, the average power (watts) is measured to be 120.
  2. Next, determine the RMS voltage. For this problem, the RMS voltage is calculated to be 6 volts.
  3. Finally, calculate the RMS Current using the formula above: 

Irms = Pave / Vrms

Inserting the values from above and solving the equation with the imputed values gives: 

Irms = 120 / 6 = 20 (amps)


Example Problem #2: 

Using the same process as example problem 1, we first define the variables outlined by the formula. In this case, the values are:

average power (watts) = 270

RMS voltage = 3 volts

Entering these values into the formula above gives : 

Irms = 270 / 3 = 90 (amps)