How to Use the Percentage Calculator
Select the calculation mode you need using the tabs above, enter your numbers, and the result appears instantly — no need to click a button.
- X% of Y — Find a percentage of any number. Great for discounts, tips, and tax calculations.
- X is what % of Y — Find what percentage one number is of another. Useful for grades, statistics, and comparisons.
- % Change — Calculate the percentage increase or decrease between two values. Perfect for tracking growth, price changes, and performance.
- Markup vs Margin — Convert between markup and margin percentages and calculate selling price from cost. Essential for business pricing.
How to Calculate Percentages
Finding X% of a number
To find X% of Y, multiply Y by X and divide by 100. For example, to find 25% of 80: 80 × 25 ÷ 100 = 20.
Finding what percent X is of Y
Divide the part by the whole and multiply by 100. For example, 45 is what percent of 180? Answer: 45 ÷ 180 × 100 = 25%.
Calculating percentage change
Subtract the old value from the new value, divide by the absolute value of the old value, and multiply by 100. A positive result is an increase; negative is a decrease.
Markup vs margin
Markup and margin are two ways to express profit as a percentage. Markup is based on cost: (selling price − cost) ÷ cost × 100. Margin is based on selling price: (selling price − cost) ÷ selling price × 100. A 100% markup always equals a 50% margin.
Common Percentage Calculations
| Calculation | Formula | Example |
|---|---|---|
| X% of Y | Y × X ÷ 100 | 15% of 200 = 30 |
| X is what % of Y | X ÷ Y × 100 | 30 is 15% of 200 |
| % increase | (new − old) ÷ old × 100 | 50 to 75 = +50% |
| % decrease | (old − new) ÷ old × 100 | 100 to 80 = −20% |
| Markup to margin | markup ÷ (100 + markup) × 100 | 50% markup = 33.3% margin |