Percentage Calculator
Calculate percentages instantly. Find what percent of a number, percentage change, and more.
What is X% of Y? — Find a percentage of a number
X is what % of Y? — Find what percentage one number is of another
Percentage Change — From one value to another
Increase/Decrease by % — Add or subtract a percentage
Quick Reference Table
| Percentage | Fraction | Decimal | Value |
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About Percentage Calculator
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 used everywhere: discounts, tax rates, interest rates, statistics, grades, tips, and more. This calculator handles the four most common percentage problems you'll encounter.
The first calculator answers "What is X% of Y?" — the most common percentage question. For example, "What is 20% of 150?" Simply multiply 150 by 0.20 to get 30. The second calculator reverses the question: "50 is what percent of 200?" Divide 50 by 200 and multiply by 100 to get 25%. The third calculator finds the percentage change between two values — essential for comparing prices, stocks, or any before-and-after values. The fourth lets you increase or decrease a number by a percentage, useful for calculating discounts, taxes, or markups.
The quick reference table below shows common percentages of any number you enter, along with their equivalent fractions and decimals. This is helpful for mental math and quick lookups.
FAQ
Q: How do I calculate a percentage?
A: To find X% of Y, multiply Y by X/100. For example, 15% of 80 = 80 × 0.15 = 12. To find what percent X is of Y, divide X by Y and multiply by 100.
Q: What is percentage change vs percentage difference?
A: Percentage change measures the change from an old value to a new value: ((new - old) / old) × 100. Percentage difference compares two values without a clear "before" and "after": |a - b| / ((a + b) / 2) × 100.
Q: How do I reverse a percentage?
A: If a price is $80 after a 20% discount, the original price was $80 / (1 - 0.20) = $100. If a value is $120 after a 20% increase, the original was $120 / 1.20 = $100.
Q: Is my data safe?
A: Yes. All calculations happen locally in your browser. Nothing is sent to any server.