Percentage calculator
Pick the calculation you need, enter the values, and get the result instantly.
100% private — your files are processed on your device and never uploaded to a server.
How it works
- 1
Pick a calculation
Choose what you need: a percentage of a value, what percent one number is of another, an increase, a decrease, or the difference between two numbers.
- 2
Enter the values
Fill in the two number fields — decimals are supported.
- 3
Read the result
The result updates automatically as you type, no button required.
How percentages are calculated
A percentage expresses a proportion out of 100. To find X% of Y, multiply Y by X and divide by 100 (for example, 20% of 150 is 150 × 20 ÷ 100 = 30). To find what percent X is of Y, divide X by Y and multiply by 100.
A percentage increase adds that percentage to the base value (useful for markups or raises), while a percentage decrease subtracts it (perfect for discounts and sales). Percentage difference compares two existing values and shows how much they differ relative to their average.
Frequently asked questions
How do I calculate 20% of a number?
Multiply the number by 20 and divide by 100. For example, 20% of 150 is (150 × 20) ÷ 100 = 30.
How do I know what percent one number is of another?
Divide the first number by the second and multiply by 100. For example, 30 is (30 ÷ 150) × 100 = 20% of 150.
What's the difference between percentage increase and percentage difference?
A percentage increase applies a percentage to a base value to get a new one. Percentage difference compares two existing values and shows how much they vary relative to their average.
Does this calculator support decimals or negative numbers?
Yes — you can enter decimals and negative numbers wherever it's mathematically meaningful, such as in variations.