％ Percentage Calculator
Calculate X% of a number, what percentage one number is of another, or the percentage change between two numbers.
What is X% of Y?
X is what percent of Y?
Percentage increase / decrease
About Percentage Calculator
This page combines the three percentage calculations people look up most often: finding X% of a number (like calculating a tip or discount), finding what percent one number is of another (like a test score or completion rate), and finding the percentage change between two numbers (like a price increase or a change in traffic). Each uses a different formula, which is why they're kept as separate mini-calculators rather than one generic tool.
"What is X% of Y?" multiplies: (X ÷ 100) × Y. "X is what percent of Y?" divides and rescales: (X ÷ Y) × 100. Percentage change between a starting value and an ending value is ((end − start) ÷ start) × 100 — a positive result is an increase, a negative result is a decrease. All three reduce to the same underlying idea: a percentage is a ratio expressed out of 100.
One common mix-up worth knowing: percentage change isn't symmetric. If a value increases by 50%, decreasing it by 50% afterward doesn't return it to the original number — because the second percentage is calculated from a different (larger) base. This trips people up in things like reversing a price hike or a discount.
Frequently asked questions
How do I calculate a discount?
Use "What is X% of Y?" with the discount percentage and original price, then subtract the result from the original price.
How do I calculate percentage change?
Use the third calculator — enter the starting ("from") and ending ("to") values to see the percent increase or decrease.
What's the difference between a percentage point and a percent change?
If a rate goes from 20% to 25%, that's a 5 percentage point increase, but a 25% relative increase (since 5 is 25% of the original 20). Percentage points measure the raw difference; percent change measures the relative difference — mixing the two up is a common source of confusion.
Why doesn't a 50% increase followed by a 50% decrease return to the original number?
Because each percentage is calculated from a different base. Increasing 100 by 50% gives 150; decreasing 150 by 50% gives 75, not 100. The math isn't reversible unless you use the correct offsetting percentage, which depends on the new base value.
How do I calculate a raise or price increase?
Use the third calculator with your old value as "from" and your new value as "to" — it returns the percentage increase directly. To go the other direction (add a known percentage to a number), use the first calculator to find the increase amount, then add it to the original.