Percentage Calculator
Enter any two values and see every percentage answer at once — a percentage of a number, one number as a percent of another, and the percent change between them.
The percentage in question one; the starting or smaller value elsewhere.
The base number; the ending value for percent change.
X% of Y
30.00
- X is what percent of Y
- 7.50
- % change from X to Y (+ = up)
- 1,233.3
- Difference (Y − X)
- 185.00
How it works
Most percentage calculators make you pick a mode first. This one skips that: all three classic questions are answered simultaneously from the same two inputs. The three formulas: • Percentage of a number: X ÷ 100 × Y. “What is 15% of 200?” → 15 ÷ 100 × 200 = 30. • One number as a percent of another: X ÷ Y × 100. “15 is what percent of 200?” → 7.5%. • Percent change: (Y − X) ÷ |X| × 100. Going 15 → 200 is a +1,233% increase; the sign tells you direction and the absolute value in the denominator keeps decreases working symmetrically. Percent change and percent difference are not the same thing — change compares an old value to a new one (direction matters), while difference compares two unrelated values against their average. Use this calculator for before/after questions; for comparing two independent measurements, divide their gap by their average instead.
Frequently asked questions
How do I calculate a percentage of a number?
Convert the percent to a decimal and multiply: 15% of 200 = 0.15 × 200 = 30. This calculator’s first result does exactly that — enter the percent as Value X and the number as Value Y.
How do I work out percent change?
Subtract the old value from the new one, divide by the OLD value, and multiply by 100. A negative result means a decrease. The third row of results above handles it — just put the starting figure in Value X and the ending figure in Value Y.
Why does percent change use the old value in the denominator?
Because change is measured relative to where you started. Going from 50 to 75 is a 50% increase (25 ÷ 50), but going from 75 back down to 50 is only a 33.3% decrease (25 ÷ 75). Same gap, different baselines — which is why discounts and rebounds never feel symmetrical.
What is the difference between percent change and percentage points?
Percentage points are simple subtraction between two percentages: interest rising from 4% to 6% is +2 points but a 50% change. News headlines mix these up constantly — if both figures are already percentages, subtract and say “points.”