Percentage Calculator
Calculate percentages, percentage change, and percentage of a value instantly.
How to use Percentage Calculator
- Choose which type of percentage calculation you need: 'X% of Y', '% change', or 'X is what % of Y'.
- Enter your numbers into the input fields.
- The result updates instantly — no button press required.
- Use the copy button to copy the result, or reset to start over.
About this tool
The Percentage Calculator helps you solve the three most common percentage problems: finding what percent one number is of another, finding a percentage of a number, and calculating the percentage increase or decrease between two values. All calculations run instantly in your browser as you type — nothing is uploaded or sent to a server.
Frequently Asked Questions
How do I calculate a percentage of a number?
Multiply the number by the percentage, then divide by 100. For example, 20% of 50 is (20 × 50) ÷ 100 = 10. The calculator above does this instantly — just enter the two values.
How do I calculate percentage increase or decrease?
Subtract the original value from the new value, divide the result by the original value, then multiply by 100. A positive result is a percentage increase; a negative result is a percentage decrease.
Is my data uploaded anywhere?
No. This calculator runs entirely in your browser using JavaScript. Your numbers are never sent to a server.