What is a percentage?
A percentage is a number expressed as a share of 100. 25% means 25 out of every 100, which is 0.25 as a decimal or 1/4 as a fraction. Percentages make it easy to compare parts of different sized wholes, like a discount on two prices or growth in two budgets.
Most everyday percentage questions come down to one of the four rows above: finding a part, finding a rate, measuring a change, or applying a change.
Percentage formulas
How to use the percentage calculator
- 1Find the row that matches your question, for example "What is the percentage change from X to Y?".
- 2Type your two numbers. The answer and a sentence explaining it update as you type.
- 3Copy one answer with the button next to it, or copy all answers or a link that keeps every number.
Percent change vs. percentage points
When the numbers you compare are already percentages, say which change you mean. If an interest rate goes from 4% to 5%, it rose by 1 percentage point. Measured with the percentage change formula, the rate itself grew by 25%. Both statements are correct, but they answer different questions.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. 15% of 80 is 0.15 × 80 = 12.
How do I calculate a percentage increase or decrease?
Subtract the old value from the new value, divide by the old value and multiply by 100. Going from 80 to 100 is (100 − 80) ÷ 80 × 100 = 25%, an increase.
Why does a 10% increase followed by a 10% decrease not give the original number?
The second percentage is taken from a different base. 100 plus 10% is 110, and 110 minus 10% is 99, because 10% of 110 is 11.
What is the difference between percent and percentage points?
Percentage points describe the gap between two percentages. A rate that moves from 4% to 5% rises by 1 percentage point, which is a 25% increase in the rate itself.
Is my data stored anywhere?
No. Every calculation runs in your browser. Your numbers only end up in a link if you choose to copy one.