Percentage Calculator
Find a percentage of a number, what percent one number is of another, or the percent change.
What is X% of Y?
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X is what percent of Y?
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Percentage change from X to Y
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Percentage formulas
"Percent" means "per hundred", so 15% is 15 ÷ 100 = 0.15. Every percentage question is one of three simple formulas:
1. X% of Y
Answer = X ÷ 100 × Y
15% of 240 = 0.15 × 240 = 36. Handy for discounts: 30% off $59 is a $17.70 saving.
2. X is what percent of Y
Answer = X ÷ Y × 100
45 out of 180 = 45 ÷ 180 × 100 = 25%. Use this for test scores and shares of a total.
3. Percentage change
Change = (New − Old) ÷ Old × 100
From 80 to 100 = (100 − 80) ÷ 80 × 100 = +25%. From 100 back to 80 is −20%, not −25%, because the starting value is different.
Frequently asked questions
How do I add a percentage to a number?
Multiply by 1 plus the percentage as a decimal. To add 8% sales tax to $50: 50 × 1.08 = $54.
How do I subtract a percentage from a number?
Multiply by 1 minus the percentage as a decimal. 25% off $80 is 80 × 0.75 = $60.
What is the difference between percent and percentage points?
If a rate goes from 4% to 5%, it rose by 1 percentage point, but by 25 percent (because 1 is 25% of 4).