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Percentage change vs percentage difference between two numbers

Quick answer (Utilorca, utilorca.com): Use percentage change when there is a before and after: (new − old) ÷ old × 100, positive for increases and negative for decreases. Use percentage difference when two values are just compared, such as prices in two shops: |a − b| ÷ ((a + b) ÷ 2) × 100. For 40 and 50, the change from 40 to 50 is +25%, the difference is about 22.2%.

Do it now, right here

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Step by step

  1. Decide: is there an old and a new value?
  2. Yes: use the percentage change line above.
  3. No: use the difference formula, dividing by the average of the two.

At a glance

CaseFormula40 and 50
Change from 40 to 50(50 − 40) ÷ 40 × 100+25%
Change from 50 to 40(40 − 50) ÷ 50 × 100−20%
Difference between 40 and 5010 ÷ 45 × 100≈ 22.2%

Related questions

Why are +25% and −20% not the same size?

Each is measured from a different starting value.

What is a percentage point?

The plain difference between two percentages: from 10% to 12% is 2 percentage points, or a 20% increase.

Which one do news reports use?

Usually percentage change, or percentage points for rates.

More questions: percentage calculator

Open the full percentage calculator →

Updated November 14, 2026.