Four tools in one. Calculate any percentage instantly — no formula memorisation needed.
A percentage is a number expressed as a fraction of 100. The word "percent" literally means "per hundred" — so 25% means 25 out of 100.
For example: what percentage is 45 of 180? Answer: (45 ÷ 180) × 100 = 25%
For example: what is 20% of £350? Answer: 350 × (20 ÷ 100) = £70
For example: a price went from £80 to £100. Change: ((100 − 80) ÷ 80) × 100 = 25% increase.
| Question | Formula | Example |
|---|---|---|
| What is 10% of X? | X ÷ 10 | 10% of £250 = £25 |
| What is 20% of X? | X ÷ 5 | 20% of £250 = £50 |
| What is 25% of X? | X ÷ 4 | 25% of £250 = £62.50 |
| What is 50% of X? | X ÷ 2 | 50% of £250 = £125 |
| What is 15% of X? | (X ÷ 10) + (X ÷ 20) | 15% of £250 = £37.50 |
| Add 20% VAT | X × 1.2 | £250 + VAT = £300 |
| Remove 20% VAT | X ÷ 1.2 | £300 ex VAT = £250 |
Common percentages you'll encounter in the UK:
| Context | Rate | Notes |
|---|---|---|
| VAT (standard) | 20% | Most goods and services |
| VAT (reduced) | 5% | Energy, children's car seats |
| Basic rate tax | 20% | £12,571 – £50,270 |
| Higher rate tax | 40% | £50,271 – £125,140 |
| National Insurance | 8% | Employee Class 1 (2025/26) |
| Restaurant tip | 10-15% | 12.5% is standard in London |
| eBay final value fee | 12.8% | Most categories |
| Stamp duty (£250K+) | 5% | First-time buyer threshold: £425K |
Finding 10%: Just move the decimal point one place left. 10% of £247 = £24.70.
Finding 5%: Find 10%, then halve it. 5% of £247 = £12.35.
Finding 15%: Find 10% + 5%. 15% of £247 = £24.70 + £12.35 = £37.05.
Finding 1%: Move the decimal two places left. 1% of £247 = £2.47. Then multiply for any percentage.