Percentage Calculator
Find what a percentage of a number is, what percent one number is of another, and the percentage change between two values.
How to use this calculator
- Choose the type of percentage problem from the dropdown.
- Enter the two values. The helper text under each field tells you what it represents in the selected mode.
- Press Calculate to see the result together with the exact arithmetic used.
The formula
Percentage = (Part ÷ Whole) × 100- Part
- The portion you are measuring
- Whole
- The total or base value (cannot be zero)
How it works
A percentage is a fraction out of 100. “25%” simply means 25/100, or 0.25. To find a percentage of a number, convert the percentage to a decimal (divide by 100) and multiply.
To express one number as a percentage of another, divide the part by the whole and multiply by 100. For change, divide the difference by the starting value — the sign tells you whether it went up or down.
Worked example
You scored 42 out of 56 on a test and want your score as a percentage.
- 1Part = 42, Whole = 56
- 242 ÷ 56 = 0.75
- 30.75 × 100 = 75
You scored 75%.
When this calculator is useful
- Test and exam scores
- Discounts and sale prices
- Tax and tip amounts
- Comparing changes in prices, weights, or statistics
Frequently asked questions
How do I find 20% of 80?
Convert 20% to a decimal (20 ÷ 100 = 0.20) and multiply: 0.20 × 80 = 16.
What is the difference between percentage change and percentage difference?
Percentage change compares a new value to a specific starting value and has a direction. Percentage difference compares two values symmetrically against their average and has no direction.
Why can't the whole be zero?
Finding 'what percent A is of B' divides by B. Division by zero is undefined, so there is no meaningful percentage.