About this tool
Calculate % of, % change and % difference in one tool.
The Percentage Calculator covers the three most common percentage questions on a single page. Mode 1: What is X% of Y? — find a portion of a number. Mode 2: X is what percent of Y? — express one number as a percentage of another. Mode 3: Percentage change from X to Y — find the increase or decrease between two values. All modes update as you type.
Example
15% of 200 → 30 · % change 80 to 100 → +25% · % difference between 80 and 100 → 22.2%
How to use
- Select the mode you need (% of, % is of, % change).
- Enter the numbers.
- Result updates instantly.
- Use the swap button to reverse a calculation.
Features
- Three modes: % of, % is of, % change
- Real-time calculation
- Increase / decrease detection
- Shows the formula
- One-click copy of result
Frequently Asked Questions
How do I calculate 15% of 80?+
Use "What is X% of Y?" mode. Enter 15 for X and 80 for Y. Result: 12.
How do I find a percentage change?+
Use "Percentage change" mode. Enter the original value first and the new value second. The tool shows the increase or decrease.
How do I reverse a percentage calculation?+
Use the "X is what % of Y?" mode with the known result and total, or use the swap button.
Does it handle decimal percentages?+
Yes. Enter values like 3.5% or 0.75% — the tool handles fractional percentages accurately.
What does "percentage difference" mean?+
The absolute change between two numbers divided by their average × 100. E.g. between 80 and 100: (|80−100| / ((80+100)/2)) × 100 = 22.2%.
How is percentage change different?+
Percentage change measures change relative to the starting value: (new − old) / old × 100. Percentage difference uses the average of both.