How to calculate percentages
A percentage is just a fraction of 100. The three most common everyday questions each have a simple formula:
- X% of Y = (X ÷ 100) × Y — e.g. 20% of 150 = 30
- X is what % of Y = (X ÷ Y) × 100 — e.g. 30 is 20% of 150
- % change = ((New − Old) ÷ Old) × 100 — e.g. 80 → 100 is a 25% increase
What's the difference between percentage points and percent?
Going from 10% to 15% is a 5 percentage-point rise, but a 50% increase. They're different things.
How do I remove a percentage (like tax)?
To find the pre-tax price from a total, divide by (1 + rate). e.g. £120 including 20% tax = 120 ÷ 1.2 = £100.