Scientific tool

Percentage Calculator

Q: What's the difference between percent change and percentage points?

Percent change is relative to the starting value. Percentage points are a simple difference between two percentages — these are easy to mix up.

Three common percentage calculations in one place — each updates live as you type.

X is what % of Y

is what % of

X% of Y

Percent change from X to Y

From

Formulas

X is what % of Y → (X ÷ Y) × 100
X% of Y → (X ÷ 100) × Y
Percent change → ((Y − X) ÷ X) × 100

1Worked example: 25 is what % of 200 → (25 ÷ 200) × 100 = 12.5%. Percent change from 50 to 75 → ((75−50) ÷ 50) × 100 = 50% increase.

Edge cases: "X is what % of Y" and percent change are undefined when the denominator (Y, or the starting value) is zero — the calculator reports this explicitly instead of showing Infinity or NaN.

Common questions

What's the difference between percent change and percentage points?

Percent change is relative to the starting value (e.g. going from 50 to 75 is a 50% increase). Percentage points are a simple difference between two percentages (e.g. going from 50% to 75% is a 25 percentage point increase) — these are easy to mix up and give very different numbers.

Why is percent change undefined when starting from zero?

Percent change measures growth relative to the starting value. Dividing by a starting value of zero is mathematically undefined — there's no meaningful "percent" of nothing to compare against, regardless of what the new value is.