Percentage calculator

1. Find the block that answers your question: “What is a percentage of an amount?”, “What percentage is one number of another?”, “Percentage increase or decrease” or “Add or subtract a percentage”.
2. Fill in the block's two fields. You can type decimals with a comma (“12,5”) or a full stop (“12.5”).
3. In “Add or subtract a percentage”, first choose whether to add (an increase or mark-up) or subtract (a discount).
4. The result appears below straight away. Click the copy button to take it to another app.

A percentage is a fraction of 100. To find 15 % of 80, multiply 80 by 15 and divide by 100: 80 × 15 / 100 = 12.

To find what percentage one amount is of another, divide the part by the total and multiply by 100. If 30 out of 120 people answered a survey, 30 / 120 × 100 = 25 %.

To add or subtract a percentage, multiply by 1 plus or minus the percentage as a decimal. A €200 price with a 15 % discount becomes 200 × 0.85 = €170; with a 15 % increase, 200 × 1.15 = €230.

You can also work backwards: if you know 12 is 15 % of an amount and want to find that amount, divide 12 by 15 and multiply by 100: 12 / 15 × 100 = 80. It is the sum you need, for example, to find the total budget behind a line item you already know.

Percentage change tells you how much a value has changed relative to where it started: subtract the starting value from the final value, divide by the starting value and multiply by 100. If a website's visits go from 80 to 100, the change is (100 − 80) / 80 × 100 = 25 %. If they fall from 100 to 80, it is −20 %.

Note that going up 25 % and down 20 % are not symmetrical: it depends on which value is the starting point. That is why something that falls 20 % and then rises 20 % does not get back to where it was. This calculator always uses the starting value as the base.

Mixing up percentage points and percentages: going from 10 % to 12 % is a rise of 2 percentage points, but 20 % in relative terms. Adding up chained discounts: 10 % and then another 10 % is not 20 % but 19 %, because the second applies to the already reduced price. And removing a tax by subtracting its percentage: to remove VAT you divide, not subtract; for that, use the VAT calculator in this same section.