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Percentage Calculator
To find a percentage, multiply the number by the percent and divide by 100. For example, 15% of 80 is 80 × 15 ÷ 100 = 12. This calculator handles every common phrasing and shows the exact steps for your numbers.
These are example numbers. Type your own to replace them.
What is X% of Y?
80 × 15 ÷ 100 = 12
X is what percent of Y?
12 ÷ 80 × 100 = 15%
X is P% of what?
12 ÷ 15 × 100 = 80
Percentage increase / decrease
(75 − 50) ÷ 50 × 100 = 50%
Percentage difference
|40 − 60| ÷ |(40 + 60) ÷ 2| × 100 = 40%
Percent off a price
80 − 25% (20 off) = 60
Results display up to 4 decimal places. Any finite number works; division by zero is called out instead of showing ∞.
How percentages work
A percentage is a fraction of 100. "Percent" literally means "per hundred," so 15% is the same as 15/100, or 0.15. Every percentage problem is one of three questions, and each has one formula:
| Question | Formula | Example |
|---|---|---|
| What is P% of Y? | Y × P ÷ 100 | 15% of 80 = 12 |
| X is what % of Y? | X ÷ Y × 100 | 12 of 80 = 15% |
| X is P% of what? | X ÷ P × 100 | 12 at 15% → 80 |
Percentage change vs. percentage difference
Percentage change compares a new value against an original value, so it has a direction: going from 50 to 75 is a 50% increase, and going from 80 to 60 is a 25% decrease. The original value is always the base of the division.
Percentage difference compares two values with no "before" and "after", such as two prices from two stores. It divides the gap by the average of the two values, which makes it symmetric: 40 and 60 differ by 40%, in either order.
Common fractions as decimals and percentages
Values marked ≈ are rounded to two decimal places; the underlying decimal repeats forever.
| Fraction | Decimal | Percentage |
|---|---|---|
| 1/2 | 0.5 | 50% |
| 1/3 | 0.333… | ≈ 33.33% |
| 2/3 | 0.666… | ≈ 66.67% |
| 1/4 | 0.25 | 25% |
| 3/4 | 0.75 | 75% |
| 1/5 | 0.2 | 20% |
| 1/6 | 0.1666… | ≈ 16.67% |
| 1/8 | 0.125 | 12.5% |
| 3/8 | 0.375 | 37.5% |
| 5/8 | 0.625 | 62.5% |
| 7/8 | 0.875 | 87.5% |
| 1/10 | 0.1 | 10% |
| 1/100 | 0.01 | 1% |
Common mistakes
A 50% increase followed by a 50% decrease does not return to the start: 100 → 150 → 75. The decrease acts on the larger base. This is also why a stock that drops 50% must gain 100% to recover.
Percentage points and percent are different units. Going from a 10% rate to a 12% rate is a rise of 2 percentage points, but a 20% relative increase.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percent, then divide by 100. Example: 15% of 80 = 80 × 15 ÷ 100 = 12.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. Example: 12 is 12 ÷ 80 × 100 = 15% of 80.
What is the difference between percentage change and percentage difference?
Percentage change compares a new value to an original value and has a direction (increase or decrease). Percentage difference compares two values of equal standing against their average, so it has no direction.
Can a percentage be greater than 100?
Yes. 150% of 40 is 60. Percentages above 100 simply mean more than the whole.
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Written by the CalculatorJam editorial team. Formulas and edge cases are documented on this page and verified by automated reference tests. Last updated . Read our editorial policy.
Sources: Wolfram MathWorld: Percent