Percentage Calculator
Solve common percentage problems.
How to use the Percentage Calculator
The Percentage Calculator is free and runs entirely in your browser — no sign-up, and nothing you enter leaves your device. It opens pre-filled with a realistic example, so you can see how it works before replacing any figure with your own; the results update as you type. Press Calculate to refresh the result panel, or Reset to return to the example.
The inputs it asks for:
- Calculation Type — choose one — X% of Y, X is what % of Y, % Change from X to Y.
- X — a number.
- Y — a number.
The formula
Three everyday percentage problems, each a one-line calculation:
X% of Y = (X ÷ 100) × Y
X is what % of Y = (X ÷ Y) × 100
% change = ((Y − X) ÷ X) × 100- X, Y
- the two numbers you enter
- % change
- measured relative to the starting value X
Percentage change always uses the starting value as its base, which is why a rise then an equal-percent fall doesn't return to the original number.
Worked example
Using the example values — Calculation Type X% of Y, X 15, Y 240 — the Percentage Calculator returns a 15% of 240 of 36.00.
Prefer your own numbers? Change any field above and this recomputes instantly.
Key terms
- Percent
- A fraction out of 100 — 25% means 25 per hundred, or 0.25.
- Base value
- The number a percentage is taken of (the "Y" in "X% of Y").
- Percentage points
- The plain difference between two percentages — distinct from percent change.
Frequently asked questions
What's the difference between percent and percentage points?
Going from 10% to 12% is a rise of 2 percentage points, but a 20% increase. Points are the absolute gap; percent change is relative to the start.
How is percent change calculated?
Subtract the old value from the new, divide by the old value, and multiply by 100. A negative result is a decrease.
Why isn't a 50% drop undone by a 50% rise?
Because the base changes. 100 down 50% is 50; 50 up 50% is only 75 — the rise is taken on the smaller number.