Percentage calculator
Percentages of numbers, percentage change, and increases or decreases by a percentage.
What is 15% of 200?
30
15% of 200
Show workings
- Working15 ÷ 100 × 200 = 30
How it works
- X% of Y: divide X by 100 and multiply by Y. 15% of 200 = 0.15 × 200 = 30.
- X as a % of Y: divide X by Y and multiply by 100. 30 out of 200 = 15%.
- % change: the difference divided by the starting value, × 100. From 80 to 100 is +25%; from 100 to 80 is −20%.
- Increase or decrease by X%: multiply by 1 + X/100 (or 1 − X/100).
Worked example
A price rises from £80 to £100: the change is £20, and £20 ÷ £80 × 100 = 25%. If it then falls back by 25%, it ends at £75, not £80, because the 25% is now of the bigger number.
Questions
Why isn’t a 20% fall undone by a 20% rise?
Each percentage is of a different starting number. 100 down 20% is 80; 80 up 20% is 96. To get back to 100 from 80 you need a 25% rise.
What is a percentage point?
The plain difference between two percentages. A rate going from 4% to 5% rises by 1 percentage point, which is a 25% increase in the rate itself.
Is X% of Y the same as Y% of X?
Yes. 8% of 50 and 50% of 8 are both 4, which can make mental maths easier.