Percentage calculator
Work out percentages four ways, with the working.
This percentage calculator covers the four sums people need most: what X percent of a number is, what percentage one number is of another, the percentage change between two values, and adding or taking off a percentage. Enter your numbers and the answer appears at once, with the working underneath.
How to work out a percentage
Per cent means out of a hundred. To find a percentage of a number, multiply the number by the percentage and divide by 100. 20% of 150 is 150 times 20 divided by 100, which is 30.
To find what percentage one number is of another, divide the part by the total and multiply by 100. If you score 45 out of 60 in a test, that is 45 divided by 60 times 100, or 75%. Whenever you know two of the three values, you can always work out the third.
Percentage increase and decrease
To work out a change, take the old value from the new one, divide the difference by the old value and multiply by 100. A price that goes from £80 to £100 has risen by 25%. If it falls back from £100 to £80, the fall is 20%, not 25%, because this time you divide by 100. That difference is the most common mistake with percentages.
Example: a pay rise
Your salary goes from £30,000 to £31,500. Choose percentage change and enter both figures. The difference of £1,500, divided by £30,000, is 0.05, a rise of 5%. To see what a 3% rise on £30,000 would be, choose add or take off a percentage: £30,000 plus 3% is £30,900. For VAT on a price there is a separate VAT calculator, and for scaling one quantity to another the ratio calculator.
Frequently asked questions
How do I work out a percentage of a number?
Multiply the number by the percentage and divide by 100. 20% of 150 is 150 times 20 divided by 100, which is 30.
How do I find what percentage one number is of another?
Divide the part by the total and multiply by 100. 45 out of 60 is 75%.
How do I calculate a percentage increase?
Take the old value from the new one, divide by the old value and multiply by 100. From 80 to 100 is an increase of 25%.
Why does a 25% rise followed by a 25% fall not get me back to the start?
Because each percentage is taken of a different value. From 80 to 100 is 25% more, but from 100 back to 80 is only 20% less.
Is the percentage calculator free?
Yes. It is free, needs no sign up, works on your phone and does not store the numbers you enter.
Made by Kashif Sulehria, Lahore
Updated on