Percentage Calculator
Percent of a number, percent change and ratios.
About this tool
The Percentage Calculator answers the three percentage questions everyone needs: what is X% of Y, X is what percent of Y, and the percentage change between two numbers. Each calculation updates live as you type — no submit button.
Percentage change uses the standard formula (new − old) ÷ |old| × 100, so an increase from 50 to 65 shows +30% and a drop from 65 to 50 shows −23.08%. Results are rounded to four decimal places.
Frequently asked questions
Because the base changes. Going 50→65 is measured against 50, but 65→50 is measured against 65 — that asymmetry is correct math, not an error.
Yes, all three calculators accept any real number, including decimals and negative values.
Use the first row: 25% of 80 gives 20, so the sale price is 80 − 20 = 60.