Percentage Calculator
Three everyday percentage questions in one place. Type in any box and the answer updates instantly.
What is X% of Y?
- 15% of 80
- 12
X is what percent of Y?
- 30 is this percent of 120
- 25%
Percentage change from X to Y
- Increase
- 30%
- Difference
- 15
How it’s calculated
A percent is a number out of 100. The three questions use these formulas:
X% of Y = X ÷ 100 × Y
X as a percent of Y = X ÷ Y × 100
Change from X to Y = (Y − X) ÷ |X| × 100
A positive change is an increase and a negative change is a decrease. The change is measured against the starting value X.
Examples
Discount and share
A 15% discount on an 80 item is 15 ÷ 100 × 80 = 12 off. If 30 out of 120 people replied, the reply rate is 30 ÷ 120 × 100 = 25%.
Increase and decrease
A price going from 50 to 65 is (65 − 50) ÷ 50 × 100 = a 30% increase. Going from 80 down to 60 is (60 − 80) ÷ 80 × 100 = a 25% decrease.
Frequently asked questions
What is the difference between percent change and percentage points?
Percentage points measure the plain difference between two percentages, while percent change compares it to the starting value. A rate moving from 4% to 5% is up 1 percentage point, which is a 25% increase.
Why does a 25% rise followed by a 20% fall return to the start?
Each change is measured from a different base. 100 up 25% is 125; 125 down 20% is 100. The same percentage up and then down does not cancel out: 100 up 10% is 110, and down 10% is 99.
Why can’t I calculate the change from zero?
Percent change divides by the starting value. Dividing by zero has no defined result, so any increase from zero cannot be expressed as a percentage. Describe it as an absolute change instead.
How do I add a percentage to a number?
Multiply by 1 plus the percentage as a decimal. Adding 8% to 250 is 250 × 1.08 = 270. To remove a percentage that was already added, divide: 270 ÷ 1.08 = 250.
Is percent change the same as percent difference?
No. Percent change uses the starting value as the base and has a direction. Percent difference compares two values with no start or end, usually dividing by their average, so the results differ.
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Results are estimates for general information and are not financial, medical or legal advice.