Everyday maths
Percentage calculator
Find a percentage of a number, compare two values or work out a percentage change.
Calculate a percentage
Choose the calculation you need, enter both values, then select Calculate.
Three ways to use a percentage
Find a portion
15% of 80 is 12. Divide 15 by 100, then multiply by 80.
Compare a part
20 out of 80 is 25%. Divide the part by the whole, then multiply by 100.
Measure change
A rise from 80 to 100 is 25%. Divide the difference by the original amount, then multiply by 100.
A note on the starting value
A percentage change needs an original amount greater than zero. The calculator explains when a whole is zero or an input cannot produce a useful result. Displayed numbers are rounded, so use the unrounded value if a precise financial or scientific calculation matters.