Percentage Calculator
This percentage calculator handles the three questions people ask most: What is X% of a number? What percentage is one number of another? And by what percent did a value increase or decrease? Pick the mode you need and the answer updates as you type.
- 15% of 240
- 36
Percentages show up everywhere: discounts, taxes, tips, grades, interest rates, statistics. The three calculations are easy to mix up, so the formulas below make clear which one applies to your situation.
How it's calculated
X% of Y = (X ÷ 100) × Y
To find what percent X is of Y: (X ÷ Y) × 100. To find the percentage change from A to B: ((B − A) ÷ A) × 100, where positive means an increase and negative a decrease. Note the change is always measured relative to the starting value A.
Worked example
What is 15% of 240? (15 ÷ 100) × 240 = 36. What percent is 45 of 180? (45 ÷ 180) × 100 = 25%. If a price rose from $80 to $92, the change is ((92 − 80) ÷ 80) × 100 = +15%.
Frequently asked questions
›What is the difference between percentage change and percentage points?
If an interest rate moves from 4% to 6%, it rose by 2 percentage points but by 50% in relative terms. Percentage points compare the raw difference; percentage change compares it to the starting value.
›Why is a 50% increase not undone by a 50% decrease?
Because each change applies to a different base. 100 increased by 50% is 150; 150 decreased by 50% is 75, not 100. You would need a 33.3% decrease to return to the original.
›How do I calculate a reverse percentage?
If a price after a 20% discount is $60, divide by (1 − 0.20): $60 ÷ 0.8 = $75 original. For a value after an increase, divide by (1 + rate).
›How do I convert a fraction to a percentage?
Divide the numerator by the denominator and multiply by 100. For example, 3/8 = 0.375 = 37.5%. Our fraction to decimal converter does this for you.
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