Percentage Calculator
Use this free percentage calculator to solve the three most common percentage questions. Enter your numbers and get an instant answer — everything is calculated in your browser, so your data never leaves your device.
What is X% of Y?
X is what percent of Y?
Percentage change (increase / decrease)
How to calculate percentages by hand
Percent means "per hundred". To find a percentage of a number, convert the percent to a decimal and multiply. For example, 15% of 200 is 0.15 × 200 = 30. To find what percent one number is of another, divide the part by the whole and multiply by 100: 30 ÷ 150 × 100 = 20%.
Percentage change measures growth between an old value and a new value. Subtract the old value from the new value, divide by the old value, and multiply by 100. A positive result is an increase; a negative result is a decrease. This is commonly used for price changes, salary raises, and investment returns.
Frequently asked questions
Is my data saved? No. All calculations run locally in your browser using JavaScript. Nothing is sent to a server.
Can I use decimals? Yes, the calculator supports decimal values for all inputs.