Percentage Calculator
Pick a calculation mode, enter your two numbers, and get an instant percentage result with the working shown.
How it works
"X% of Y" scales Y down to X percent of its value. "X is what % of Y" expresses X as a fraction of Y, out of 100. "% change from X to Y" measures how much Y has grown or shrunk relative to X, as a percentage — positive for an increase, negative for a decrease.
Formula
X% of Y = (X ÷ 100) × Y | X is what % of Y = (X ÷ Y) × 100 | % change = ((Y − X) ÷ X) × 100
The same two numbers answer three different questions depending on which percentage relationship you need.
| Symbol | Variable | Unit | Description |
|---|---|---|---|
| X | First value | — | |
| Y | Second value | — |
Worked example
20% of 150
- X:
- 20
- Y:
- 150
- Mode:
- X% of Y
(20 ÷ 100) × 150 = 30.
30 is what % of 150
- X:
- 30
- Y:
- 150
- Mode:
- X is what % of Y
(30 ÷ 150) × 100 = 20%.
Change from 150 to 180
- X:
- 150
- Y:
- 180
- Mode:
- % change from X to Y
((180 − 150) ÷ 150) × 100 = 20% increase.
Frequently asked questions
Why is percent change negative sometimes?
A negative result means Y is smaller than X — a decrease. For example, going from 200 to 150 is a -25% change.
What's the difference between percentage points and percent change?
Percentage points are a simple difference between two percentages (e.g. 25% to 30% is a 5 percentage-point rise), while percent change measures relative growth (that same move is a 20% increase).
Can X or Y be negative?
Yes for "X% of Y" and "% change", where negative values make sense (e.g. a loss). "X is what % of Y" requires Y to be nonzero.
Why can't Y be zero in "X is what % of Y"?
Dividing by zero is undefined. If Y is 0, the question "what percent of 0 is X" has no meaningful answer.
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Last reviewed: 2026-08-22.