Math
Percentage Calculator
Three modes: calculate percentages, find what percent one number is of another, or measure percentage change.
What is X percent of Y?
Private by design
Calculator results are estimates based on your inputs. They are useful for learning, planning, and comparison, but they are not professional advice.
Use responsibly
Use the result as a practical first pass, then verify any important decision with the appropriate source or professional.
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Percentage formulas used
- X% of Y = (X / 100) × Y
- X is what % of Y = (X / Y) × 100
- % change from X to Y = ((Y - X) / |X|) × 100
Common percentage examples
- 15% of 200 = 30
- 30 is 15% of 200
- Going from 80 to 100 = +25% change
- Going from 100 to 80 = -20% change
Why percentage change is not symmetric
A 20% decrease followed by a 20% increase does not return you to the original number. Starting at 100: -20% = 80, then +20% of 80 = 96, not 100. This is why percentage change always specifies direction.