Percentage Calculator Online — Free
Runs 100% in your browser — your files never leave your device.
Discounts, tips, growth rates, grade curves — percentage math is daily life, and the questions people ask are always one of the same three. This calculator answers all of them side by side with live results as you type: what is X% of Y, X is what percent of Y, and the percent change from X to Y.
How it works
- 1
Pick your question
Three cards cover the three percentage questions: of, is-what-percent, and change.
- 2
Type the numbers
Results appear live as you type — no equals button needed.
- 3
Read the answer
Undefined cases (like change from zero) explain themselves instead of failing silently.
About this tool
The three percentage questions
Every percentage problem is one of three shapes: what is X percent of Y, what percent is X of Y, and X is what percent of Y changed from what. The calculator handles all three — pick the shape, enter two numbers, and the third answers itself.
Where percentages trip people up
Percent changes compound and reverse asymmetrically: a 50 percent drop needs a 100 percent rise to recover. Percentage points are not percentages either — moving from 10 to 15 percent is 5 percentage points, a 50 percent increase. The tool computes the plain math; naming the question correctly is your half.
Everyday use
Tips, discounts, tax, markup, growth rates, and test scores — all one of the three shapes above. Enter the numbers you have and read the one you need.
Frequently asked questions
How do I calculate a discount?
Use the "what is X percent of Y" shape: the discount is the percent off times the price. Subtract the result from the price for the final amount.
What is the difference between percentage and percentage points?
Percentage points measure the raw gap between two percentages; percentage measures the relative change. Going from 10% to 15% is 5 points but a 50% increase.
Can I use decimal percentages?
Yes — 2.5 percent works like any other value, and the result carries the precision through.