Three ways to work out percentages. Type your numbers and get instant answers — no button needed.
To find X% of a number, divide X by 100 and multiply by the number. For example, 20% of 150 is (20 ÷ 100) × 150 = 30. This works for any percentage — whether you're working out a tip at a restaurant, a discount on a sale item, or how much VAT to add to a price.
Divide the part by the whole and multiply by 100. For example, if you scored 35 out of 50 on a test, that's (35 ÷ 50) × 100 = 70%. This calculation comes up constantly — from exam results to sales targets, investment returns to recipe scaling.
Subtract the old number from the new number, divide by the old number, and multiply by 100. If something went from £80 to £100, that's ((100 − 80) ÷ 80) × 100 = 25% increase. If it went from £100 to £80, that's ((80 − 100) ÷ 100) × 100 = −20% decrease. Notice the percentage isn't the same in both directions — a common mistake.
Finding 10% of any number is easy — just move the decimal point one place to the left. So 10% of 250 is 25. From there you can quickly work out other percentages: 5% is half of 10%, 20% is double 10%, and 1% is 10% divided by 10. For example, to find 15% of 80: 10% is 8, 5% is 4, so 15% is 12. These mental shortcuts are faster than reaching for a calculator.
Percentages are everywhere in daily life. Sale discounts (30% off), tax rates (20% VAT), exam scores (scored 85%), pay rises (3% increase), mortgage rates (4.5% APR), battery level (67% charged), and tipping (15-20% at restaurants) all use percentages. Understanding how to calculate them quickly saves time and helps you make better financial decisions.
A jacket costs £120 and has 25% off. To find the discount: 25% of £120 = (25 ÷ 100) × 120 = £30 off. So you pay £120 − £30 = £90. A quick shortcut: 25% is a quarter, so just divide by 4. £120 ÷ 4 = £30 discount. If you want to use our calculator, type 25 and 120 into calculator 1 above.
Your salary goes from £28,000 to £29,400. What percentage rise is that? Use calculator 3 above — from 28000 to 29400. The answer is 5%. To check: 5% of £28,000 = £1,400, and £28,000 + £1,400 = £29,400. You can also use our salary calculator to see how a pay rise affects your take-home pay after tax.