Percentage Calculator
Solve percentage of a number, percentage change, and percent increase/decrease instantly.
X% of Y
(X / 100) × Y
X is what % of Y
(X / Y) × 100
% change from X to Y
((Y − X) / X) × 100
X increased/decreased by Y%
X × (1 ± Y / 100)
Find whole: X is Y% of what?
X / (Y / 100)
About the Percentage Calculator
A percentage is just a fraction out of 100, and every calculation here is a variation on one relationship: part = (percent / 100) × whole. Rearranging which value is unknown gives the five modes on this page — solve for the part, the percent, the whole, or the new value after a percentage change or adjustment. For example, a $200 item marked up by 15% (X% of Y, then increase) becomes 200 × 1.15 = $230, and if that same $230 later drops back to $200, the percentage decrease isn't 15% but ((230 − 200) / 230) × 100 ≈ 13.04% — a common source of confusion since increase and decrease percentages between the same two numbers are never equal.
To use it: type into either input field of any panel and its result updates immediately — no submit button needed. Each of the five panels is independent, so you can work multiple percentage problems side by side (say, comparing a discount calculation against a year-over-year growth calculation) without your inputs interfering with each other, and copy just the result you need with its dedicated copy button.