Percentage Calculator
Calculate percentages with ease. Find what percentage a number is of another, calculate percentage of a value, percentage change, and more.
Calculation Type
Enter values above to calculate the result
Table of Contents
What is a Percentage?
A percentage is a way of expressing a number as a fraction of 100. The word "percent" comes from the Latin "per centum," meaning "by the hundred." Percentages are denoted using the percent sign (%).
Percentages are used extensively in everyday life, from calculating discounts and sales tax to measuring changes in stock prices, analyzing statistics, and understanding probability. They provide a standardized way to compare values and understand proportions.
For example, if you score 85 out of 100 on a test, you scored 85%. If a store offers a 20% discount, you'll pay 80% of the original price. Understanding percentages is essential for financial literacy and data interpretation.
How it Works
Percentages can be calculated using a simple formula: (Part / Whole) × 100 = Percentage. Our calculator handles four common percentage calculations:
- Percentage of a Number: Calculate what a certain percentage is of a given number
- Percentage Comparison: Determine what percentage one number is of another
- Percentage Change: Calculate the percentage increase or decrease between two values
- Finding the Whole: Find the total value when you know a part and its percentage
All calculations are performed in real-time as you enter values, providing instant results without needing to click a button. The calculator automatically handles decimals and provides clear error messages for invalid inputs.
Calculation Types
What is X% of Y?
This calculates a percentage of a given number. For example, "What is 20% of 100?" results in 20.
Formula: (X / 100) × Y = Result
X is what % of Y?
This determines what percentage one number represents of another. For example, "20 is what % of 100?" results in 20%.
Formula: (X / Y) × 100 = Percentage
% Change from X to Y
This calculates the percentage increase or decrease between two values. For example, "Percentage change from 100 to 120" results in a 20% increase.
Formula: ((Y - X) / X) × 100 = Percentage Change
If X is Y%, what is the whole?
This finds the total value when you know a part and its percentage. For example, "If 20 is 20%, what is the whole?" results in 100.
Formula: (X / Y) × 100 = Whole
Common Use Cases
- Discounts & Sales: Calculate sale prices, discounts, and savings on purchases
- Tips & Gratuities: Calculate tip amounts for restaurant bills or service providers
- Tax Calculations: Determine sales tax, VAT, or income tax amounts
- Finance & Investing: Calculate returns, interest rates, and portfolio changes
- Grade Calculations: Determine test scores, final grades, and weighted averages
- Business Analytics: Analyze growth rates, market share, and performance metrics
- Budgeting: Allocate percentages of income to different expense categories
- Statistics: Understand survey results, poll data, and statistical analysis
- Health & Fitness: Track weight loss, body fat percentage, and progress goals
Examples
Example 1: Discount Calculation
Question: What is 25% of $80?
Answer: 25% of $80 = $20. So the discount is $20, and the sale price would be $60.
Example 2: Test Score
Question: You scored 42 out of 50. What percentage did you get?
Answer: 42 is 84% of 50. You scored 84%.
Example 3: Price Increase
Question: A product price increased from $50 to $65. What is the percentage increase?
Answer: The percentage change from $50 to $65 is a 30% increase.
Example 4: Finding Total
Question: If $15 is 15% of the total, what is the total amount?
Answer: If $15 is 15%, the whole is $100.
Frequently Asked Questions
To calculate a percentage of a number, multiply the number by the percentage divided by 100. For example, to find 20% of 100: (20 / 100) × 100 = 20. You can use our "What is X% of Y?" calculator mode for this calculation.
Divide the part by the whole and multiply by 100. For example, to find what percentage 25 is of 100: (25 / 100) × 100 = 25%. Use our "X is what % of Y?" calculator mode for this calculation.
Subtract the original value from the new value, divide by the original value, and multiply by 100. For example, if something increases from 100 to 120: ((120 - 100) / 100) × 100 = 20% increase. Use our "% Change from X to Y" calculator mode for this calculation.
Yes! Our calculator accepts decimal values for both numbers and percentages. For example, you can calculate 12.5% of 100, or find what percentage 33.33 is of 100.
A percentage point is the absolute difference between two percentages. For example, if something increases from 10% to 15%, that's a 5 percentage point increase, but a 50% relative increase (since 15 is 50% more than 10).
Compound interest requires calculating percentages repeatedly over time. While our calculator handles basic percentage calculations, compound interest involves applying percentage growth multiple times. For compound interest, you'd need to multiply the principal by (1 + rate/100) raised to the power of the number of periods.
Yes, negative percentages represent decreases. When calculating percentage change, negative results indicate a decrease. For example, if something decreases from 100 to 80, the percentage change is -20%, meaning a 20% decrease.
Our calculator performs precise calculations and displays results to 2 decimal places. The calculations use standard mathematical formulas and should match results from other percentage calculators or manual calculations.