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Percentage Change Calculator

Find the percentage increase or decrease between two values.

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Percentage change
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Human-checked guide

Percentage Change Calculator explained clearly

Quick answer: Use this calculator to compare an old value with a new value and see the increase or decrease as a percentage.

Core formulaPercentage change = ((new value − old value) ÷ old value) × 100.

This is the main rule used by the calculator, written in plain language so you can check the result.

Worked exampleIf a price rises from 40 to 50, the change is ((50 − 40) ÷ 40) × 100 = 25%.

Examples are rounded where needed, so final values may differ slightly from payroll, school, or accounting systems.

How to read itA positive result means an increase. A negative result means a decrease. The old value is the baseline, so changing the baseline changes the percentage.

Use the result as a decision aid, then confirm important school, work, or payroll decisions with the official source.

Common mistakes to avoid

  • Swapping the old and new values
  • Trying to divide by zero
  • Confusing percentage points with percentage change

Methodology

The calculator subtracts the old value from the new value, divides by the old value, and converts the result to a percentage.

Reviewed by CalcBeacon Editorial TeamUpdated June 2026Category: Everyday Math & TimeDuplicate-section checked

Frequently asked questions

Can percentage change be negative?

Yes. A fall from the original value produces a negative change.

What if the starting value is zero?

Percentage change cannot be calculated in the usual way from zero.

Where is this useful?

It is useful for finance, ecommerce, schoolwork and everyday comparisons.

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