Calculate percentages and percentage change
💡 The Math Behind the Deals That "25% off" sign? This calculator helps you figure out the real price — and whether it is actually a deal. Great for shopping, calculating tips, or understanding your business profit margins.
The word "percent" comes from the Latin "per centum," meaning "by the hundred" — the % symbol itself evolved over centuries from a shorthand abbreviation of that phrase used by Italian merchants.
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What is a Percentage Calculator? A percentage calculator performs three common percentage operations: finding what percentage one number is of another, calculating a percentage of a number, and measuring percentage change between two values.
How Percentage Calculations Work The basic percentage formula is (part/whole) × 100. For finding X% of Y, multiply Y by X and divide by 100. For finding what percentage X is of Y, divide X by Y and multiply by 100.
What is X% of Y? This mode calculates the actual value of a percentage. Example: What is 25% of 200? Answer: 50. Useful for calculating discounts, tips, tax amounts, or any portion of a total.
X is what % of Y? This mode finds the percentage relationship. Example: 25 is what % of 200? Answer: 12.5%. Useful for understanding proportions, test scores, or market share.
Percentage Change (X to Y) This mode measures increase or decrease between two values. Formula: ((new - old)/old) × 100. A positive result means increase, negative means decrease. Essential for tracking growth, sales, or price changes.
Using Your Results Use percentage calculations for shopping discounts, tip calculation, profit margins, grade percentages, and any scenario where you need to express a number as a fraction of 100.
Example: Say you want to know what 25% of 200 is. Multiply 200 by 25, then divide by 100: (25 ÷ 100) × 200 = 50. Switch to "% Change" mode and go from 200 to 250, and you'd get a +25% increase.
Multiply Y by X and divide by 100. For example, 25% of 200 is (25 ÷ 100) × 200 = 50.
Use the formula ((new − old) ÷ old) × 100. A positive result means an increase, a negative result means a decrease.
Divide the smaller number by the larger number and multiply by 100. For example, 25 is what % of 200? 25 ÷ 200 × 100 = 12.5%.