Percentage Calculator
Calculate percentages three ways: find the percent, find the value, or find the total.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Request a ToolHow to Use the Percentage Calculator
This calculator handles the three most common percentage questions. Select a mode, enter two numbers, and get your answer instantly. No buttons to click. Results update as you type.
- Choose your calculation mode. The dropdown gives you three options. "X is what % of Y" finds the percentage relationship between two numbers. "What is X% of Y" applies a percentage to a number. "X is Y% of what" finds the total when you know a part and a percentage.
- Enter your two values. The labels update to match the selected mode, so you always know what goes where. Both fields accept decimals.
- Read the result. The answer appears immediately with the formula used shown below. Use Copy to grab the result or Share to send a pre-filled link to someone.
Common uses include calculating discounts, figuring out tax amounts, grading tests, computing tips, and working out proportional splits. The tool works with any numbers, including decimals and negatives.
About Percentage Calculations
A percentage expresses a number as a fraction of 100. The word comes from the Latin "per centum," meaning "by the hundred." Percentage calculations are among the most frequently used math operations in daily life, from shopping discounts to financial analysis to academic grading.
The three modes in this calculator cover virtually every percentage question you will encounter. The formulas are straightforward: division for finding a percentage, multiplication for applying one, and division again for finding the base. All calculations run in your browser with zero data sent to any server.
Frequently Asked Questions
How do I calculate what percent one number is of another?
Divide the part by the whole, then multiply by 100. For example, 25 is what percent of 200? Answer: (25 / 200) x 100 = 12.5%. Select the "X is what % of Y" mode, enter 25 and 200, and the calculator does the rest.
How do I find a percentage of a number?
Multiply the percentage (as a decimal) by the number. For example, what is 15% of 80? Answer: (15 / 100) x 80 = 12. Use the "What is X% of Y" mode and enter 15 and 80.
What does "X is Y% of what" mean?
This mode finds the total when you know a part and its percentage. For example, 30 is 20% of what? Answer: 30 / (20 / 100) = 150. This is useful when you know a discount amount and the discount rate, and you want the original price.
Can I use negative numbers?
Yes. The calculator accepts negative numbers in all fields. Negative percentages and values work correctly with the standard formulas. This can be useful for loss calculations or temperature conversions.