Percentage Calculator UK

Work out any percentage in seconds: a percentage of a number, what percentage one number is of another or the percentage change between two values. Every example below uses everyday UK situations, from VAT and sale discounts to pay rises and exam marks.

The Three Formulas That Solve Everything

Almost every percentage question you will ever meet is one of these three:

1. What is X% of Y? Formula: (X ÷ 100) × Y. So 15% of £250 is 0.15 × 250 = £37.50.
2. X is what percentage of Y? Formula: (X ÷ Y) × 100. Scored 45 out of 60 in a test? 45 ÷ 60 = 0.75, so 75%.
3. Percentage change from A to B: Formula: ((B − A) ÷ A) × 100. Rent rising from £1,200 to £1,350 is (150 ÷ 1,200) × 100 = a 12.5% increase.

The same change formula handles decreases. A price dropping from £120 to £90 is (90 − 120) ÷ 120 × 100 = −25%, a 25% fall.

Everyday UK Percentage Examples

• VAT: The UK standard rate is 20%. To add VAT to a net price, multiply by 1.2, so £50 + VAT is £60. To find the pre-VAT price from a VAT-inclusive figure, divide by 1.2, so a £60 receipt contains £10 of VAT on a £50 net price. Learn more at our VAT Calculator UK.
• Sale discounts: For 25% off an £80 jacket, multiply by 0.75 to get £60 in one step. The general shortcut: multiply by (1 − discount ÷ 100). Try our Percentage Off Calculator UK.
• Pay rises: A salary going from £35,000 to £36,750 is a rise of (1,750 ÷ 35,000) × 100 = 5%. Take a look at your post-tax earnings with our Salary Calculator UK.
• Tips and bill splitting: 10% of any bill is the total with the decimal point moved one place left, £64.30 becomes £6.43. For 15%, take 10% and add half of it again.
• Deposits: A 10% deposit on a £240,000 house is £24,000. A 5% deposit is half that at £12,000.

Mental Maths Shortcuts

The 10% trick: Move the decimal one place left. From there, build anything: 5% is half of 10%, 20% is double, 1% is 10% divided by 10.

The flip trick: X% of Y always equals Y% of X. Struggling with 8% of 50? Flip it: 50% of 8 is 4. Same answer, far easier.

Doubling checks: A 100% increase means the value has doubled. A 200% increase means it has tripled. If your answer implies otherwise, recheck the working.

Quick decimal conversions: 25% = 0.25 = one quarter. 20% = 0.2 = one fifth. 50% = 0.5 = one half. 75% = 0.75 = three quarters.

Percentage Change, Difference and Points

These three sound similar but mean different things and mixing them up is a very common percentage mistake.

• Percentage change: compares a new value to an original: ((new − original) ÷ original) × 100. There is a clear starting point.
• Percentage difference: compares two values with no obvious original, dividing the gap by their average: |A − B| ÷ ((A + B) ÷ 2) × 100. Useful for comparing two prices or two measurements.
• Percentage points: measure the arithmetic gap between two percentages. If a savings rate moves from 4% to 5%, it rises by 1 percentage point, but that is a 25% relative increase. News headlines regularly blur this distinction, so it pays to know it.

Reverse Percentages

A reverse percentage finds the original value before a percentage was applied, and it catches people out because you cannot just take the percentage off the final figure.

If a coat costs £68 after a 15% discount, the £68 represents 85% of the original price. Divide by 0.85 to get the original £80. The same logic removes VAT: a £120 invoice including 20% VAT is 120 ÷ 1.2 = £100 net. The rule: divide the final amount by the decimal it represents. Use our Reverse Percentage Calculator UK to solve this step-by-step.