Percentage Calculator
Work out a percentage of a number, what percent one number is of another, and percentage increase or decrease.
What is X% of Y?
—
X is what percent of Y?
—
Percentage increase or decrease
—
Add or subtract a percentage
—
How it works
Four percentage calculators on one page, all updating as you type. What is X% of Y? multiplies your number by the percentage divided by 100 — so 15% of 200 is 200 × 0.15 = 30. X is what percent of Y? divides the part by the whole and multiplies by 100, which is how you turn a score like 25 out of 200 into 12.5%. Percentage increase or decrease takes the difference between the old and new value, divides it by the old value and multiplies by 100, so 50 → 75 is a 50% increase. The last calculator adds or subtracts a percentage from a starting number, handy for markups, raises and price cuts.
Results are rounded to at most six decimals and use thousands separators so big numbers stay readable. Every calculation runs in JavaScript inside your browser — no numbers are sent anywhere, there is no sign-up and there are no ads. Use the Copy button next to any answer, or download all four results as a plain text file.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 15% of 200 is 200 × 0.15 = 30. Type both values into the first calculator above and the answer appears as you type — no Calculate button needed.
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100. So 25 out of 200 is (25 ÷ 200) × 100 = 12.5%. The second calculator does this for you and warns you if the whole is zero, because nothing can be a percentage of zero.
How do I calculate percentage increase or decrease?
Subtract the old value from the new value, divide by the old value and multiply by 100. Going from 50 to 75 is ((75 − 50) ÷ 50) × 100 = a 50% increase; a negative result is a decrease. The third calculator labels the result for you.