Percentage Calculator
Five percentage calculators on one page. Fill in any box and the answer updates instantly.
Percentage of a number
One number as a percentage of another
Percentage change
Increase or decrease by a percentage
Find the original number
Percentage formulas
| Question | Formula | Example |
|---|---|---|
| X% of Y | X ÷ 100 × Y | 15% of 80 = 12 |
| X as a % of Y | X ÷ Y × 100 | 12 of 48 = 25% |
| % change | (new − old) ÷ old × 100 | 50 → 65 = +30% |
| Increase X by Y% | X × (1 + Y ÷ 100) | 200 + 10% = 220 |
| Reverse % | X ÷ Y × 100 | 30 is 25% of 120 |
Everyday examples
- Shopping: 30% off £45 = £45 × 0.7 = £31.50.
- Pay rise: a 4% rise on £28,000 = £28,000 × 1.04 = £29,120.
- Exam marks: 54 out of 72 = 54 ÷ 72 × 100 = 75%.
- Tipping: 12.5% service on £64 = £8.
Working with prices and tax? Try the VAT calculator.
Common questions
How do I work out a percentage of a number?
Divide the percentage by 100 and multiply by the number. 15% of 80 = 0.15 × 80 = 12.
How do I calculate percentage increase?
Subtract the old value from the new value, divide by the old value and multiply by 100. From 50 to 65: (65 − 50) ÷ 50 × 100 = 30% increase.
How do I find the original number before a percentage was added?
Divide by 1 plus the percentage as a decimal. If a price is £120 after a 20% rise, the original was £120 ÷ 1.2 = £100.
Why does a 50% fall followed by a 50% rise not get me back to where I started?
Because the second percentage is applied to a smaller number. £100 falls 50% to £50, then rises 50% to only £75. You would need a 100% rise to get back to £100.
What is the difference between percent and percentage points?
If an interest rate goes from 4% to 5%, it has risen by 1 percentage point, but by 25 percent in relative terms.