A percentage point (pp) is the arithmetic difference between two percentages. If unemployment rises from 4% to 6%, it rose by 2 percentage points. A percent change (%) is that difference expressed as a proportion of the starting value: (6 − 4) / 4 × 100 = 50%. So the same change is either '2 percentage points' or '50 percent' depending on which framing you use — and both are mathematically correct but describe entirely different magnitudes.
The confusion is common because casual language uses 'percent' for both. 'Unemployment rose by 2 percent' is ambiguous: it could mean the rate went from 4.00% to 4.08% (a 2% relative change) or from 4% to 6% (a 2 percentage point absolute change). In precise technical and scientific writing, 'percent' refers to relative change and 'percentage points' refers to absolute change.
Where this confusion causes real errors
Politicians and marketers often exploit this ambiguity. A policy that raises a tax from 10% to 12% can be described as 'a 2 percentage point increase' (sounds small) or 'a 20% tax increase' (sounds large). Both are accurate. Voters and consumers need to know which framing is being used to evaluate the actual impact.
In drug trials, absolute vs relative risk reduction is the same distinction. A drug that reduces heart attack risk from 2% to 1% has reduced risk by 1 percentage point (absolute) or by 50% (relative). Pharmaceutical advertising often highlights the relative reduction because it sounds more impressive, while absolute reduction is what actually matters to individual patients — a 1 percentage point reduction means you need to treat 100 people to prevent 1 heart attack.
How to communicate clearly
When writing about changes in rates, proportions, or percentages, always specify: are you reporting an absolute difference (use 'percentage points') or a relative difference (use 'percent' or '%')? The standard conventions in statistics and journalism are: use 'percentage points' for the arithmetic difference between two rates, and reserve 'percent' for relative change (new minus old, divided by old, times 100).
For clarity in calculations: percentage change = ((new value − old value) / |old value|) × 100, expressed as %. Percentage point change = new percentage − old percentage, expressed as pp or percentage points. The percentage calculator handles both types of calculation and labels them explicitly to eliminate ambiguity.