Enter two different related values into the calculator to determine the relative percent difference (RPD) between them.

RPD Formula

The following formula is used to calculate a relative percent difference (RPD.)

RPD = [X2-X1] / [[X2+X1]/2] *100

  • Where RPD is the relative percent difference (%)
  • X2 is the final value
  • X1 is the initial value

To calculate relative percent difference (RPD), take the difference between the final and initial value and divide it by the sum of the values over 2, then multiply by 100.

RPD Definition

What is RPD?

RPD, short for relative percent difference, is a measure of the change in a value relative to the average of that value.

For example, if a value in an experiment changed from 10 to 20, the RPD would be relative to the average of those two numbers. 10 + 20 /2 = 15.

Example Problem

How to calculate RPD?

  1. First, determine the initial value.

    For this example problem, we will look at the price of a TV over time. The initial price of the TV is found to be $500.00.

  2. Next, determine the final value.

    After two years time, the TV price goes up to $750.00.

  3. Finally, calculate the RPD.

    The relative percent difference is then calculated using the formula above:
    RPD = [X2-X1] / [[X2+X1]/2] *100
    RPD = [750-500] / [[750+500]/2] *100
    RPD = 40%