Compare percentages and percentage points
Name the denominator and distinguish a change in a rate from a relative change.
Follow the method ↓
The answer in 30 seconds
Percentage points describe the difference between two percentages. A relative percentage change compares that difference with the starting value. The two answers can be numerically very different.
For a rate rising from 20% to 25%, the change is 5 percentage points. Relative to the initial 20%, it is a 25% increase: (25 − 20) ÷ 20 × 100. State the measure, population and dates alongside either figure.
Examples to adapt
A support rate moving from 20% to 25% rose by five points, not five percent relative.
Check the original price and whether successive discounts use different bases.
Inspect the axis and denominators before repeating a stated change.
Follow the method
- 1Identify the quantities
Record the original rate, new rate, population and period.
- 2Calculate point difference
Subtract the original percentage from the new percentage.
- 3Calculate relative change
Divide the difference by the original percentage, when it is non-zero, then multiply by 100.
- 4Label the result
Write either percentage points or percent relative change and show the denominator.
A checklist to keep
Use these checks to record what you found. The grid supports a decision; it does not make one for you.
| Check | What to examine | Action |
|---|---|---|
| Start | What is the original rate? | Record |
| End | What is the new rate? | Record |
| Points | End minus start? | Subtract |
| Relative | Difference divided by start? | Calculate |
| Base | Same population and period? | Check |
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What to check
A change in population can make rates less comparable.
Relative change from zero needs a different description; division by zero is undefined.
Rounded input rates can make a derived relative change approximate.
Common questions
Is 20% to 25% a 5% increase?
It is a five-percentage-point increase, or a 25% increase relative to the starting 20%.
Why name the denominator?
Because the same count can represent a different percentage when the group size changes.
Sources and documentation
Documentation consulted on . Examples are illustrative; interfaces and results may change.