Percentage Calculator: Percent of, percent change, increase, discount and reverse. Input: Values you enter. Output: Results shown on the page. Privacy: Runs in your browser: inputs and files stay on your device and are not uploaded.
How to use the percentage calculator
- Find the question that matches yours: a percent of a number, what percent one number is of another, percentage change, adding or removing a percentage, or working backwards to the original.
- Type your numbers into the boxes inside the sentence. The answer appears immediately, with the calculation underneath.
The formulas
- X% of Y = X ÷ 100 × Y. 20% of 150 is 30.
- X is what % of Y = X ÷ Y × 100. 30 out of 120 is 25%.
- Percentage change = (new − old) ÷ |old| × 100. From 80 to 100 is +25%; from 100 to 80 is −20%. The two are not symmetrical because the starting value differs.
- Increase by X% = Y × (1 + X/100), and decrease (discount) = Y × (1 − X/100).
- Reverse percentage: if 45 is 30% of a number, the number is 45 ÷ 0.30 = 150. Use this to find a price before tax or a discount.
- Percentage difference compares two values with no "before" and "after": |A − B| ÷ the average of A and B × 100.
A common mistake is to undo a percentage by applying the same percentage in reverse. A price that rises 25% and then falls 25% ends up 6.25% lower, because the fall is taken from the larger number. Use the reverse card to get back to an original value.
All calculations happen instantly in your browser.
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. 15% of 60 = 0.15 × 60 = 9.
What is the difference between percentage change and percentage difference?
Percentage change has a direction, from an old value to a new one. Percentage difference treats both values equally and divides by their average.
What is the difference between percent and percentage points?
If an interest rate goes from 4% to 5%, it rises by 1 percentage point, but by 25 percent. Both are correct; they measure different things.