Percentage Calculator
Find any percentage: X% of Y, what percent X is of Y, and percent change.
This calculator handles the three most common percentage problems. Choose the mode that matches your question, enter the two numbers, and the result updates instantly.
Mode 1 answers 'what is X% of Y' — for example, 20% of 150 is 30. Mode 2 answers 'X is what percent of Y' — for example, 30 is 20% of 150. Mode 3 computes the percentage change between two values, useful for price changes, growth rates and discounts.
All calculations happen in your browser as you type; nothing is sent to any server.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 25% of 200 = 200 × 25 ÷ 100 = 50. The first mode of this calculator does this for you.
How do I calculate percentage increase?
Subtract the old value from the new value, divide by the old value, then multiply by 100. Use the percent change mode above to get the answer instantly.
Can I use decimals or negative numbers?
Yes. The calculator accepts decimals and negative values, and percent change handles decreases correctly by showing a negative result.