Percentage calculator is a calculator tool that solves the three most common percentage problems. It computes X% of Y, finds what percent X is of Y, and measures percentage change between two values, showing the formula alongside the result. The tool runs in your browser.
Direct links for each type of percentage calculation.
(X/100) * Y. X is what % of Y: (X/Y) * 100. Percentage change from A to B: ((B - A)/A) * 100.Number arithmetic; no external library.NaN or infinity when Y is zero. Standard floating-point rounding applies to repeating decimals.Reviewed and tested May 25, 2026.