Calculate any percentage in seconds
Find a percentage of a number, what percent one number is of another, or the percent increase or decrease between two numbers.
Common percentage reference chart
A quick lookup for common percentages of frequently used base numbers.
| Percent | of 100 | of 500 | of 1000 |
|---|---|---|---|
| 5% | 5 | 25 | 50 |
| 10% | 10 | 50 | 100 |
| 15% | 15 | 75 | 150 |
| 20% | 20 | 100 | 200 |
| 25% | 25 | 125 | 250 |
| 50% | 50 | 250 | 500 |
| 75% | 75 | 375 | 750 |
Need a different percent or base number? Use the percentage calculator above.
About the percentage calculator
A percentage is just a fraction of 100 — "20 percent" means 20 out of every 100. That simple idea covers almost every real-world percentage question, but the exact math you need depends on what you already know and what you're trying to find, which is why this tool offers three separate modes instead of a single formula.
The first mode, "X% of Y," answers questions like "what is 20% of 150?" by multiplying the percent (converted to a decimal) by the base number: (20 ÷ 100) × 150 = 30. This is the version most people mean when they say "percentage calculator," and it covers everyday tasks like figuring out a tip, a sales discount, or a commission.
The second mode, "X is what % of Y," flips the question around — instead of finding a piece of a whole, you already have both numbers and want to know the relationship between them. Dividing X by Y and multiplying by 100 answers questions like "30 is what percent of 150?" (answer: 20%). This mode is common in test scores, survey results, and any time you're comparing a part to a total.
The third mode, percent change, measures how much a number grew or shrank between two points: ((new − old) ÷ old) × 100. A positive result means an increase, a negative result means a decrease. This is the formula behind price changes, population growth, salary raises, and year-over-year comparisons — and it's easy to get backwards if you divide by the wrong number, so this calculator always divides by the original (starting) value.
One thing worth remembering across all three modes: a percentage is relative to whatever base you use, so a "20% increase" followed by a "20% decrease" does not return you to the original number — the decrease is calculated on a larger base. Keeping the three formulas separate, as this calculator does, helps avoid that kind of mix-up.
What is X% of Y?
Common percentages of common numbers, already calculated.
Percentage calculator questions
How to calculate percentages, percent change, and more.
How do I calculate X% of a number?
Divide the percent by 100, then multiply by the number. For example, 20% of 150 is (20 ÷ 100) × 150 = 30. Use the "X% of Y" mode above and enter the percent and the number to get an instant answer.
How do I find out what percent one number is of another?
Divide the first number by the second, then multiply by 100. For example, 30 is what percent of 150? (30 ÷ 150) × 100 = 20%. Use the "X is what % of Y" mode above.
How do I calculate percent increase or decrease?
Subtract the original value from the new value, divide by the original value, then multiply by 100: ((new − old) ÷ old) × 100. A positive result is a percent increase, a negative result is a percent decrease. Use the "% change" mode above.
What's the difference between a percentage and a percentage point?
A percentage point is the raw difference between two percentages, while a percentage change is relative. If a rate goes from 10% to 15%, that's a 5 percentage point increase, but a 50% relative increase (since 5 is 50% of the original 10).
How do I calculate a percentage discount?
Find the discount amount with the "X% of Y" mode (percent off × original price), then subtract that from the original price to get the sale price. For example, 20% off $50 is $10 off, so the sale price is $40.
Can a percentage be negative?
Yes — a percent change is negative whenever the new value is smaller than the original value, which simply represents a decrease. A plain "percentage of" calculation is negative only if you enter a negative percent or a negative base number.
How do I reverse a percentage calculation to find the original number?
If you know that X is a certain percent of an unknown number, divide X by the percent (as a decimal). For example, if 30 is 20% of a number, the number is 30 ÷ 0.20 = 150.
Why does my percent change show a very large or very small number?
Percent change is always calculated relative to the original (starting) value, so small original values can produce large percentage swings even from a modest absolute change. Doubling from 1 to 2 is a 100% increase, even though the actual change is just 1 unit.