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Math

Percentage Change Calculator

Percentage change measures relative growth or decline from an original value to a new value. Finance, retail metrics, and science KPIs use it universally.

Inputs

Enter your values below. Results update when you calculate.

About Percentage Change

Percentage change measures relative growth or decline from an original value to a new value. Finance, retail metrics, and science KPIs use it universally.

Divide the difference by the original (not the new) value unless specified otherwise.

Sign indicates increase (+) or decrease (-).

How to use this tool

Enter old and new values. Calculate percent change and absolute difference.

Formula & methodology

This percentage change calculator applies the standard relationship below. Intermediate values are kept at full precision; only the displayed result is rounded.

change% = ((new - old) / old) x 100

Worked example

A price rises from 80 to 100: change = (100 − 80) ÷ 80 × 100 = 25% increase. Note the asymmetry: falling from 100 back to 80 is only a 20% decrease, because the base is now 100.

Tips for accurate results

  • From 50 to 75 is +50%; from 75 to 50 is about -33.3%.
  • Zero old value makes percent change undefined—infinity conceptually.
  • Distinguish percentage points from percent change on percentages.
  • Use consistent units before comparing.

Frequently asked questions

100 to 120?

+20% change.

Which base?

Standard is relative to original (old) value.

Free?

Yes.

Absolute vs relative?

Tool shows both delta and percent when configured.

Further reading

Guides that explain the ideas behind this calculator.

All guides →
Math 3 min read Percentage change vs. percentage points: the mistake in most headlines From 5% to 7% is +2 points and +40% at the same time. Which one a headline chooses changes the story — here is how to read them correctly.

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