Percent vs. Percentage Points
Also known as: percentage points, relative change, absolute change.
A percentage point is the difference between two percentages; a percent change is that difference relative to the starting value.
Synthetic dataExamples on this page use synthetic data created for illustration.
Definition
A percentage point is the arithmetic difference between two percentages; a percent change is that difference relative to the starting value. Moving from 4% to 5% is a rise of one percentage point but of twenty-five percent.
In plain terms
Both describe the same movement, and both are correct, but they sound very different. Reports slide between them without warning, and a headline can use whichever sounds more dramatic. A small base makes the relative change large (a rise from 0.2% to 0.4% is “double”), while the absolute change may be negligible.
Always say which is meant, show the starting value, and be careful with arithmetic on percentages: a 50% fall followed by a 50% rise does not return to the start.
Example
| Movement | Percentage points | Percent change |
|---|---|---|
| Conversion rate 4% → 5% | +1.0 pp | +25% |
| Share of voice 24.0% → 21.4% (see Share of Voice) | −2.6 pp | −10.8% |
| Rate 0.2% → 0.4% | +0.2 pp | +100% |
| Value 100 → 50 → 75 (down 50%, then up 50%) | — | −25% overall |
A headline “conversion up 25%” and a headline “conversion up one point” describe the same event.
Common misunderstandings
- “Percent and percentage points are the same.” They are different quantities; mixing them up changes the size of the claim.
- “A big percent change means a big change.” Not when the starting value is tiny.
- “Percentages can be averaged to get the overall percentage.” Only if the groups are the same size; otherwise weight by group size.
References
- David Spiegelhalter. The Art of Statistics: How to Learn from Data . Basic Books, 2019. ISBN 978-1541618510.
- Darrell Huff. How to Lie with Statistics . W. W. Norton, 1993. ISBN 978-0393310726.