Percentage Calculator

Find a part of a whole, measure a change from an original value, or compare the difference between two values. Choose the comparison before entering A and B.

Percentage comparison

Pick the kind of comparison first; the meaning of A and B changes with the selected mode.

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CalculationValue AValue B

Choose the right comparison

Choose part-of-whole, percentage change, or percentage difference.
Enter values A and B in the order described by the selected mode.
Read the note beneath the result to confirm the comparison.

Part of a whole

Three related formulas

18 correct answers out of 24 equals 75%.

Easy ways to choose the wrong formula

Reversing the old and new values in percentage change.
Using percentage difference when one value is a baseline.
Dividing by a zero original or total.

Interpreting a change or difference

Part-of-whole compares A with B. Change treats A as the original value. Difference compares two values symmetrically using their average magnitude.

Reviewed September 2026.

Questions about Percentage Calculator

When should I use percentage difference?

Use it when neither value is the original reference, such as comparing two experimental measurements.

Why does percentage change depend on direction?

The original value is the denominator. Moving from 50 to 75 is a 50% increase; moving back is a 33.33% decrease.

Other ways to compare marks

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