Percentage Calculator
Free online percentage calculator with 6 different calculation types. Find percentages, percentage change, difference, increase, and decrease. See also Percentage Change Calculator and Decimal to Percent.
What is X% of Y?
Example: What is 25% of 200? Answer: 50
Percentage of a Number
Example: 20% of 12 = 2.4
X is what % of Y?
Example: 50 is what % of 200? Answer: 25%
X is Y% of what?
Example: 50 is 25% of what? Answer: 200
Percentage Change
Example: From 80 to 100 = 25% increase
Percentage Difference
Example: Difference between 100 and 150 = 40%
Increase / Decrease by %
Example: 500 changed by 10% = 550 (increase) or 450 (decrease)
What is a Percentage?
A percentage is a number expressed as a fraction of 100. The word comes from the Latin "per centum," meaning "by the hundred." Percentages are used everywhere in daily life — from shopping discounts and tax rates to exam scores and statistics. The symbol "%" represents percent. For example, 25% means 25 out of 100, which equals the fraction 1/4 or the decimal 0.25.
Percentage Formulas
Basic Percentage
What is X% of Y? → Answer = (X / 100) × Y
X is what % of Y? → Percentage = (X / Y) × 100
X is Y% of what? → Total = X / (Y / 100)
Percentage Change
Change = ((New − Old) / |Old|) × 100
Percentage Difference
Difference = (|A − B| / ((|A| + |B|) / 2)) × 100
Increase / Decrease
Increased value = Value × (1 + Percent / 100)
Decreased value = Value × (1 − Percent / 100)
Worked Examples
What is 15% of 200?
(15 / 100) × 200 = 0.15 × 200 = 30
45 is what % of 180?
(45 / 180) × 100 = 0.25 × 100 = 25%
Percentage change from 80 to 100?
((100 − 80) / 80) × 100 = (20 / 80) × 100 = 25% increase
500 increased by 10%?
500 × (1 + 0.10) = 500 × 1.10 = 550
Common Percentage Reference Table
| Percentage | Fraction | Decimal | Example (of 100) |
|---|---|---|---|
| 1% | 1/100 | 0.01 | 1 |
| 5% | 1/20 | 0.05 | 5 |
| 10% | 1/10 | 0.10 | 10 |
| 20% | 1/5 | 0.20 | 20 |
| 25% | 1/4 | 0.25 | 25 |
| 33.33% | 1/3 | 0.3333 | 33.33 |
| 50% | 1/2 | 0.50 | 50 |
| 66.67% | 2/3 | 0.6667 | 66.67 |
| 75% | 3/4 | 0.75 | 75 |
| 100% | 1/1 | 1.00 | 100 |
| 150% | 3/2 | 1.50 | 150 |
| 200% | 2/1 | 2.00 | 200 |
Technical Details
Percentage calculations are fundamental to mathematics, finance, science, and everyday life. In finance, percentages express interest rates, returns on investment, tax rates, and discounts. In statistics, they represent proportions, probabilities, and margins of error. In science, they express concentrations, efficiency, and error rates. This calculator handles all six common percentage operations with full decimal precision. Note that percentage change and percentage difference are different calculations — change measures relative to the starting value, while difference measures relative to the average of both values.
Frequently Asked Questions
How do I calculate a percentage?
To find X% of Y, divide X by 100 and multiply by Y. For example, 20% of 150 = (20/100) × 150 = 30.
What is the difference between percentage change and percentage difference?
Percentage change measures how much a value has changed relative to its original value (directional — increase or decrease). Percentage difference measures how far apart two values are relative to their average (non-directional — always positive).
Can a percentage be more than 100%?
Yes. A percentage over 100% means the value exceeds the reference amount. For example, if sales grew from 100 to 250, that is a 150% increase. The new value is 250% of the original.
How do I convert a percentage to a decimal?
Divide by 100. For example, 75% = 75/100 = 0.75. To convert back, multiply by 100: 0.75 × 100 = 75%.
How do I calculate a discount?
Multiply the original price by (1 − discount/100). For example, a 20% discount on $80: $80 × (1 − 0.20) = $80 × 0.80 = $64. The discount amount is $80 × 0.20 = $16.