Percentage calculator

How to use it

1. Find the line that matches your question.
2. Type your numbers into its boxes. The answer updates as you type.
3. Click the answer to copy it.

The formulas

• X% of Y = X ÷ 100 × Y. 15% of 2,400 is 0.15 × 2,400 = 360.
• X is what % of Y = X ÷ Y × 100. 36 out of 480 is 36 ÷ 480 × 100 = 7.5%.
• Percentage change = (new − old) ÷ old × 100. From 80 to 100 is 20 ÷ 80 × 100 = +25%.
• Add X% = Y × (1 + X ÷ 100). Take off X% = Y × (1 − X ÷ 100). 1,299 minus 20% is 1,039.20.

Percentage of marks

Divide the marks you got by the total marks and multiply by 100. Use the second line above: type your marks, then the total.

• One paper: 72 out of 80 is 72 ÷ 80 × 100 = 90%.
• All subjects: add the marks from every subject, add the maximum marks, then divide. Five papers of 100 with 432 marks in total is 432 ÷ 500 × 100 = 86.4%.
• Subject wise: work out each paper on its own the same way, so you can see which one pulled the total down.

Percentage off a price

For a discount, use the last line with minus: 2,000 minus 25% is 1,500, so you save 500. Two discounts in a row do not add up: 20% off and then another 10% off is 28% off in total, not 30%, because the second one is taken from the lower price.

Percentage difference between two numbers

When neither number is the starting point, such as two prices from two shops, use the percentage difference: the gap divided by the average of the two, times 100. For 80 and 100 that is 20 ÷ 90 × 100 = 22.2%. When one number came first, use percentage change on the third line instead.

Why a rise and a fall are not the same

Going from 80 to 100 is a 25% rise. Going back from 100 to 80 is a 20% fall, because the second change is measured from a bigger starting number. The same is true of discounts: a price cut by 20% needs a 25% rise to get back where it was.

Percent and percentage points

If an interest rate moves from 4% to 5%, it rose by one percentage point, but by 25 percent. News stories mix these up all the time. Use the third line above to get the percent change between two percentages.

Last checked October 2026.