Enter two different related values into the calculator to determine the relative percent difference (RPM) 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

## 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%