Percentage Calculator
Three percentage calculations in one tool: find a share, find a ratio, or find a change.
Formula
"X% of Y" is Y × X ÷ 100. "X is what % of Y" is (X ÷ Y) × 100. "% change from X to Y" is ((Y − X) ÷ X) × 100, which can be negative when Y is smaller than X.
The word percent comes from the Latin per centum, meaning "per hundred." A percentage always expresses one quantity as a fraction of 100, which is why it can be compared across completely different scales, from exam scores to interest rates.
A percentage point is a fixed unit of difference between two percentages, not a relative percentage change. If an interest rate rises from 5% to 7%, that is a 2 percentage point increase, but it is also a 40% relative increase—two correct numbers describing the same move.
Common uses
- Working out the final price of an item after a store applies a 20% discount, or checking how much sales tax will add on top of a listed price.
- Measuring how large a raise really is by turning an old and new salary into a percentage change, instead of just comparing the two numbers directly.
Frequently asked questions
- How do I calculate 20% off a price?
- Use "What is X% of Y" with X = 20 and Y = the original price to get the discount amount, then subtract it from the original price to get the final total.
- What is the difference between percent and percentage point?
- A percentage point is the plain subtraction of two percentages (7% − 5% = 2 points), while a percentage change compares that difference relative to the starting value (a 40% increase).
- Why is a 50% drop not undone by a 50% rise?
- Because each percentage is calculated on a different base. $100 dropping 50% leaves $50, and $50 rising 50% only reaches $75, not back to $100.