Enter the input voltage (V) and the input current (A) into the calculator to determine the Input Power. 

Input Power Calculator

Basic
AC Single-Phase
AC Three-Phase
Efficiency

Enter any 2 values to calculate the missing variable

Input Power Formula

The following formula is used to calculate the Input Power for DC circuits (and for AC only when using RMS values with a power factor of 1). 

IP = IV * II
  • Where IP is the Input Power (watts)
  • IV is the input voltage (volts) 
  • II is the input current (amps) 

To calculate the input power for DC, multiply the input voltage by the input current. For AC real power, power factor matters: single-phase real power is P = VRMS · IRMS · PF, and three-phase real power is P = √3 · VLL · IL · PF.

How to Calculate Input Power?

The following two example problems outline how to calculate the Input Power.

Example Problem #1:

  1. First, determine the input voltage (volts). In this example, the input voltage (volts) is measured to be 86.
  2. Next, determine the input current (amps). For this problem, the input current (amps) is measured to be 54.
  3. Finally, calculate the Input Power using the formula above: 

IP = IV * II

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

IP = 86 * 54 = 4644 (watts)

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:

input voltage (volts) = 4

input current (amps) = 56

Entering these values into the formula or calculator above gives us:: 

IP = 4 * 56 = 224 (watts)