Four everyday percentage questions answered instantly — percent of, what percent, percentage change and reverse percentage.
“Interest rates rose by 1%.” Does that mean from 4% to 5%, or from 4% to 4.04%? The difference between percent and percentage points clears this up, and once you see it you’ll spot it in headlines everywhere.
The short version
- Percentage points (pp) measure the plain difference between two percentages. 4% → 5% is +1 percentage point.
- Percent (%) change measures the relative difference. 4% → 5% is a 25% increase, because 1 is 25% of 4.
Both statements are true; they just answer different questions.
Examples
| Change | Percentage points | Percent change |
|---|---|---|
| Interest rate 4% → 5% | +1 pp | +25% |
| Unemployment 5% → 4% | −1 pp | −20% |
| Approval 40% → 50% | +10 pp | +25% |
| Conversion rate 2% → 3% | +1 pp | +50% |
| Tax rate 20% → 22% | +2 pp | +10% |
Use the “percentage change” row of the percentage calculator to get the relative change: enter the old and new rates as plain numbers.
Why it matters
Interest rates
A central bank raising rates “by 0.25%” almost always means 0.25 percentage points, often called 25 basis points (1 bp = 0.01 pp). On a $200,000 mortgage that might add around $30 a month. Model it in the loan calculator.
Medical and safety statistics
“A drug reduces risk by 50%” sounds huge. But if the risk falls from 2% to 1%, that’s only 1 percentage point: one fewer case per 100 people. Always ask for the absolute numbers.
Polls and elections
A candidate moving from 45% to 48% has gained 3 points, roughly a 6.7% relative increase in support. Journalists should say “points”, and good ones do.
Business metrics
A conversion rate going from 2% to 3% is “+1 point” but “+50%”. Both can be quoted honestly, but the second is the one that ends up in the investor deck.
How to convert
- Points from two percentages:
pp = New % − Old % - Percent change from two percentages:
% = (New − Old) ÷ Old × 100
Basis points
Finance uses basis points to avoid ambiguity entirely:
- 1 basis point = 0.01 percentage points
- 25 bp = 0.25 pp
- 100 bp = 1 pp
“Rates rose 50 basis points” can only mean one thing.
Reading headlines critically
When you see a percentage change, ask:
- Change in what? A rate, a count or an amount?
- Points or percent? If both numbers are already percentages, which kind of change is being quoted?
- From what base? A 100% rise from a tiny base can mean very little.
For the mechanics of percentage change itself, and why +50% and −50% don’t cancel out, see Percentage Increase and Decrease: How to Calculate Change Correctly. For the basic formulas, start with How to Calculate Percentages: The Only 4 Formulas You Need.
Four everyday percentage questions answered instantly — percent of, what percent, percentage change and reverse percentage.