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Math

Percentage Change Calculator

Compare an original and new value to find the relative increase or decrease.

Exact method explained belowEditable inputs

Set up your calculation

Runs on your device

SOLUTION

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter original value, new value.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

Change (%) = (new value − original value) ÷ |original value| × 100. The absolute denominator makes the direction explicit for negative starting values.

A WORKED EXAMPLE

Going from 80 to 100 is a 25% increase. Going from 100 back to 80 is a 20% decrease.

What to keep in mind

A zero original value has no finite percentage change. Negative starting values can be interpreted differently in financial reporting; this tool uses the absolute original value.

Common questions

Why are the increase and decrease not equal?

They use different starting values as denominators. The difference of 20 is 25% of 80 but only 20% of 100.

What if the original is zero?

Percentage change is undefined. Use the absolute change instead of a percentage.

Methodology maintained by ClarityKit. How these tools are built and checked.