Percentage Calculator
Calculate what percent of a number is, find percent change, and reverse-calculate any percentage. Three modes — pick the one that matches your problem, get the answer instantly.
20% of 150
30
How to use the percentage calculator
Pick a calculation type, enter your numbers, and the result updates instantly. Use 'percent of' to find a portion of a number, 'is what percent of' to find the ratio, and 'percent change' to compare two values over time.
Formula & explanation
Percent of: (X ÷ 100) × Y. Is what percent of: (X ÷ Y) × 100. Percent change: ((New − Old) ÷ |Old|) × 100. Negative percent change indicates a decrease.
Examples
20% of 150 is 30. 45 is 60% of 75. The percent change from 80 to 100 is +25%.
Frequently asked questions
- What's the difference between the three modes?
- 'X% of Y' finds a portion (e.g. 20% of 150 = 30). 'X is what % of Y' finds the ratio (e.g. 30 is 20% of 150). '% change' compares two values (e.g. from 80 to 100 is +25%).
- How is percent change calculated?
- Formula: ((New − Old) ÷ |Old|) × 100. Dividing by the absolute value of Old keeps the sign meaningful even when the starting value is negative.
- What does a negative percent change mean?
- A negative result means the value decreased. For example, a change from 100 to 75 is −25% — a 25% decrease.
- Is my data sent to a server?
- No. Every calculation runs locally in your browser. Nothing leaves your device.
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