Answers all the common percentage questions at once: X% of Y, X as a percent of Y, and the percent change from X to Y.
What it means
Almost every 'percentage' problem comes down to one of three questions: 'what is X% of Y,' 'X is what percent of Y,' or 'what's the percent change between X and Y.' This calculator answers all three at once so you don't have to remember which formula to use.
Percent change has a direction. From 50 to 80 is +60% (positive); from 80 to 50 is −37.5% (negative — and a different magnitude). The order matters. If you want a symmetric comparison, use percent difference: |X − Y| / ((X + Y) / 2).
FAQ
Division by zero — 'X as a percent of Y' returns 0 in that case rather than infinity. Same for percent change when X is 0.
Because the result is just a number (25% of 80 is 20, not '20%'). The other two outputs are inherently percentages.
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