Relative Error Calculator

Find the percent difference between a measured value and the actual value with this tool.

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Relative Error:

What it is

What is Relative Error?

Create Date: September 30, 2024

Last Modified Date: December 11, 2024

Relative error is a very simple concept, it is the difference between a measured value and the actual value expressed as a percent. Relative error is unique as it uses a percent to outline the difference in the values opposed to the actual difference between the two.

A good way to remember what relative error is can be to think of a scale from the doctor's office. When the doctor slowly and precisely is moving the gauge to find the perfect weight that makes the needle at the end sit perfectly and indicate that your weight is exactly that.

Well, the thing is there is the chance the doctor measured wrong or the scale is off a very little amount. That measured value that can be wrong when compared to the actual true value is what is being used when calculating relative error.

How to Calculate Relative Error

Relative error can be calculated with two variables, the measured value and the actual value. The formula for finding relative error with these values is:

An image showing what the formula is for relative error.
Where:
  • MV = Measured value

  • AV = Actual value

Understanding Your Results

When you use the relative error tool, you will get a single number as your result which is displayed as a percentage. This percentage is the total difference between the measured value and the actual value. The larger the percentage, the larger the difference between the values and vice versa.

If your result is 10% that means there is a 10% difference, in either direction, between the two values. That is right, since the formula uses absolute values, it takes away any negative values meaning the relative error percent will never be negative.

How to Use the Relative Error Calculator

If you need to find the relative error between two numbers you are in the right place. You can easily do this by following these steps:

  1. Enter the measured value

  2. Enter the actual, true value

  3. Hit calculate and get the relative error percentage in seconds!

Example Calculation

You have a food scale at home and like to weight out your food when you are cooking and preparing meals. You are measuring in ounces and pour an entire pack of 16oz pasta onto the scale. For some reason, the scale is reading 14oz, despite the box being 16oz.

Using our relative error tool, you can identify just how far off the measured value, 14, is from the actual value, 16. We plug 14 into the measured value field and 16 in the actual value field and then hit calculate. We got a relative error of 12.5%!

Relative Error - Frequently Asked Questions

Absolute error is the difference between measured and actual values, while relative error expresses this difference as a percentage.

No, relative error cannot exceed 100% because it represents the difference as a percentage relative to the actual value.

Yes, relative error is typically expressed as a positive percentage using the absolute value of the difference.

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