Percentage Calculator
Percent of, percent change, add/subtract percent.
About the Percentage Calculator
Four percentage modes in one tool: find X percent of Y, work out what percent X is of Y, calculate the percentage change between two values, or add and subtract a percentage from a base number. Each mode shows the exact formula being used, so the arithmetic is transparent rather than a black box.
How to use the Percentage Calculator
- Pick a mode tab: X% of Y, X is what % of Y, % change, or Add / subtract %.
- Fill the two labeled inputs for the chosen mode.
- Read the Result tile and the formula line beneath it.
- For % change, check the increase or decrease note with the absolute difference.
Percentage Calculator FAQ
How is percentage change computed?
As (new โ old) รท |old| ร 100, so going from 80 to 100 is a 25% increase, and the tool labels the direction plus the absolute amount of the change.
How does add / subtract percent work?
It multiplies the base by (1 ยฑ percent/100) โ entering 200 with +15% gives 230 โ and negative percentages subtract instead.
Why does a zero denominator show a dash?
Dividing by zero is undefined, so modes that would require it โ such as asking what percent a value is of zero โ display โ rather than a misleading number.