Percentage points versus percentage change
Compare a change from 20% to 25%, choose the correct denominator and handle zero or negative baselines explicitly.
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State the two different answers
A rate increasing from 20% to 25% rises by 5 percentage points. Relative to its starting value, it rises by 25%, because (25 − 20) ÷ 20 × 100 = 25. Both answers can be correct, but they describe different quantities. Include the word “points” when subtracting two rates directly. The comparison calculator below shows both results side by side.
Choose the denominator before calculating
For percentage change, use the original value in the denominator. From 80 to 100 is a 25% increase; from 100 back to 80 is a 20% decrease. Reversing a change does not normally produce the same percentage with the opposite sign. A discount of 20% followed by an increase of 20% produces 96 from an original 100, not a return to 100.
Handle zero and negative starting values
Relative change from zero is undefined using the ordinary formula because it divides by zero. Report the absolute change or describe the transition instead of displaying an infinite growth rate as useful information. Negative baselines can make the signed result counterintuitive. For a move from a loss to a profit, show the original and final amounts and explain the convention rather than relying on one headline percentage.
Keep the measurement consistent
Compare values covering the same population, time period and units. A conversion rate calculated from 20 visitors and a rate from 20,000 visitors have different uncertainty even when their percentages match. Round only the displayed answer, and retain the unrounded inputs for further calculations. This page explains arithmetic; it does not establish that an observed business change is statistically meaningful or caused by a particular action.