Percentage Calculator
Solve any everyday percentage question: X% of Y, X is what % of Y, and more.
About this percentage calculator
Percent means "per hundred," so every percentage problem is a multiplication or division by 100. The tricky part is knowing which number goes where. This calculator handles the three common questions — finding a percentage of a number, finding what percent one number is of another, and finding the original whole from a part — and shows the answer instantly as you type.
It's useful for grades, discounts, tax, tips, commissions, survey results and business reports. For the change between two values, use the percentage change calculator.
How to use the Percentage Calculator
- Pick the question that matches your problem.
- Enter X and Y.
- Read the answer — it updates as you type.
Percentage formulas
X% of Y = X ÷ 100 × Y · X as % of Y = X ÷ Y × 100 · Whole = X ÷ (Y ÷ 100)
Each question is a rearrangement of the same relationship: part = percent ÷ 100 × whole. Knowing any two of part, percent and whole lets you find the third.
Worked example
15% of 80 is 0.15 × 80 = 12. 12 is 12 ÷ 80 × 100 = 15% of 80. And if 12 is 15% of a number, the number is 12 ÷ 0.15 = 80.
Tips for better results
- To find 10% of anything, move the decimal one place left; 5% is half of that.
- X% of Y equals Y% of X — 8% of 50 is the same as 50% of 8.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. 25% of 200 is 0.25 × 200 = 50.
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100. 30 out of 120 is 30 ÷ 120 × 100 = 25%.
Last reviewed: October 2026 · Results are calculated in your browser.