Percentage Calculator
Easily calculate percentages from one value to another or from a percentage to a value.
What is X percent of Y?
e.g. 15% of 200 = 30
Result
X is what percent of Y?
e.g. 30 of 200 = 15%
Result
Percentage increase or decrease from X to Y?
e.g. from 100 to 150 = +50%
Result (Increase) (Decrease)
Three calculation types in one tool
Calculate percentage values (X% of Y), find the percentage share (X is what % of Y), and calculate percentage changes (increase or decrease) — all in one compact tool.
Instant results
Results are calculated in real time as you type. No button click required — just enter numbers and the result appears immediately.
100% local & private
All calculations happen in the browser. Your numbers are never sent to a server. Simple, fast and privacy-friendly.
Frequently asked questions
Answers to common questions about the percentage calculator
To calculate X percent of a number Y, multiply Y by X and divide the result by 100. Example: 15% of 200 = 200 × 15 ÷ 100 = 30. Our tool does this calculation automatically as soon as you enter the values.
To calculate what percent X is of Y, divide X by Y and multiply the result by 100. Example: 30 of 200 = 30 ÷ 200 × 100 = 15%. Division by zero is not defined, so Y must be greater than 0.
The percentage change from X to Y is calculated as: (Y − X) ÷ |X| × 100. A positive result means an increase, a negative result means a decrease. Example: From 100 to 150 = (150 − 100) ÷ 100 × 100 = +50%. If X is negative, the absolute value is used.
The absolute value of the starting value is used when calculating the percentage change so that the sign of the change can be determined correctly — regardless of whether the starting value is positive or negative. Without the absolute value, a negative starting value would reverse the sign of the result.
The tool shows up to 4 decimal places but removes trailing zeros. Integer results are displayed without a decimal point. This keeps the output readable without showing unnecessary digits.