Percentage Calculator
Percent of a number, ratios and percent change — three modes in one tool.
25% of 200 is 50.
Percentage math shows up everywhere: discounts, raises, tax shares, grade averages. This tool answers the three most common percentage questions on a single screen and shows its work.
How is it calculated?
The three modes use these formulas:
- Y% of X:
X × Y / 100. For example, 25% of a value is a quarter of it. - X is what percent of Y:
X / Y × 100. - Percent change from X to Y:
(Y − X) / X × 100. A positive result is an increase, a negative one a decrease.
Results are rounded to two decimal places. All arithmetic is integer-based, so there are no floating-point errors.
Example
A product priced at 3,450 with a 20% discount: the discount is 3,450 × 20 / 100 = 690, so the new price is 2,760. If the price later rises from 2,760 to 3,036, the change is (3,036 − 2,760) / 2,760 × 100 = 10%.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 15% of 800 is 800 × 15 / 100 = 120. Use the "What is Y% of X?" mode.
How do I find what percent one number is of another?
Divide the first number by the second and multiply by 100. For example, 30 is 30 / 150 × 100 = 20% of 150.
How is percent increase calculated?
Subtract the old value from the new one, divide by the old value, multiply by 100. From 200 to 250: (250 − 200) / 200 × 100 = 25%.
Are percentage points and percent change the same?
No. Going from 20% to 25% is a 5 percentage-point rise, but a 25% relative increase. The two are often confused.