Percentage Calculator
Three percentage calculations in one place - each answer appears instantly with the working shown.
What is X% of a number?
X is what percent of Y?
Percentage increase or decrease
How to calculate percentages
A percentage is just a fraction of 100 - "per cent" literally means "per hundred". Every percentage problem you'll meet day to day is one of the three shapes above, and each has a one-line formula:
- X% of Y - multiply:
(X ÷ 100) × Y. 15% of 80 is 12. - X is what % of Y - divide:
(X ÷ Y) × 100. 30 out of 120 is 25%. - Change from A to B -
((B − A) ÷ A) × 100. From 50 to 65 is a 30% increase.
The calculator updates as you type and shows the exact working underneath each answer, so you can follow the maths - handy for checking homework or sense-checking a discount.
Everyday examples
Working out a tip, checking a sale discount, adding VAT to an invoice or comparing this month's numbers to last month's - they're all percentage problems. A useful trick for mental maths: 10% is just the number with the decimal point moved one place, and you can build most percentages from that. 15% of 80? 10% is 8, 5% is 4, so 15% is 12.
Percentage points vs percent
If an interest rate moves from 4% to 5%, it has risen by one percentage point, but by 25 percent (because 1 is a quarter of 4). News reports mix these up constantly - now you don't have to.