How to calculate a percentage
A percentage is simply a part out of 100. To find what percent one number is of another, divide the part by the whole and multiply by 100. To find a percentage of a number, turn the percent into a decimal and multiply. This calculator covers all three everyday cases: a percent of a number, what percent one number is of another, and the percent change between two numbers.
What is the percentage formula?
Percentage = (part / whole) × 100. To take a percent of a number: result = (percent / 100) × number. For percent change: change = ((new - old) / old) × 100.
Three quick examples
What is 20% of 500? Multiply 500 by 0.20 to get 100.
30 is what percent of 200? Divide 30 by 200 and multiply by 100 to get 15%.
A price rises from 200 to 260. The change is (260 - 200) / 200 × 100, a 30% increase.
What percentage mistakes should you avoid?
The biggest one is confusing "percent of" with "percent change". Going from 200 to 260 is a 30% increase, but dropping back from 260 to 200 is only about a 23% decrease, because the starting number is different each way. And a percentage point is not the same as a percent: moving from 10% to 12% is 2 percentage points, which is actually a 20% increase.
Frequently asked questions
How do I calculate 10% of a number?
Move the decimal one place left. 10% of 250 is 25. For 20% double that; for 5% halve it.
What is the difference between percentage and percentage points?
A percentage point is the raw gap between two percentages. Going from 10% to 12% is 2 percentage points, but a 20% increase in relative terms.
How do I find a percentage increase?
Choose the '% change' mode and enter the old value as X and the new value as Y. A positive answer is an increase.
What does a negative % change mean?
It means the value went down. From 100 to 80 is a −20% change.
Can I use decimals?
Yes, both inputs accept decimals for precise results.