Percentage of a Number Calculator
Find what percentage of a number is — or calculate what percentage one number is of another. Two calculators in one, free, fast, no signup required.
What Is "Percentage of a Number"?
Finding the percentage of a number means calculating what a given percentage represents as an actual value. When someone asks "what is 20% of 150?", they want the answer in real units — not a percentage, but a number: 30. This is the most fundamental percentage calculation, used dozens of times a day in everyday life without people even thinking about it.
The reverse — finding what percentage one number is of another — answers questions like "30 is what percentage of 150?" The answer is 20%. Both calculations are two sides of the same concept: the relationship between a part, a whole, and a percentage. This percentage of a number calculator handles both directions with a single click.
Whether you need to calculate percentage of a number for a discount, a tip, a tax amount, a commission, or a test score — the formula is always the same. And whether you need to find a percentage of a number or calculate what percentage a number is of another number, both tools are available in the tabs above. This page also covers how to calculate percentages of a number mentally, how to get percentage of a number on calculator, how to work out percentage of a number on calculator, how to calculate 20 percentage of a number, how to calculate 25 percentage of a number, and how to calculate percentage of a whole number — all in one place.
The Two Most Common Scenarios
Scenario 1: Find X% of Y
"What is 15% of $80?" — you know the percentage and the total, and want the actual amount. Used for tips, discounts, taxes, commissions, and any time you need to find a portion of a whole.
Scenario 2: X is what % of Y?
"30 out of 150 is what percentage?" — you know both numbers and want the percentage relationship. Used for test scores, pass rates, market share, and any time you need to express a ratio as a percentage.
How to Calculate Percentage of a Number
Formula 1: Find X% of a Number
To calculate percentage of a number, multiply the number by the percentage and divide by 100.
or equivalently:
Result = Number × (Percentage ÷ 100)
Examples:
20% of 150 = 150 × 20 ÷ 100 = 30
25% of 200 = 200 × 25 ÷ 100 = 50
15% of 80 = 80 × 15 ÷ 100 = 12
8.5% of 1,200 = 1,200 × 8.5 ÷ 100 = 102
Quick mental shortcut: To find 10% of any number, just move the decimal point one place to the left. 10% of 350 = 35. Then double it for 20% (70), halve it for 5% (17.5), or add them for 15% (52.5). This is the fastest way to calculate percentages of a number in your head without a calculator.
Formula 2: Find What Percentage One Number Is of Another
To calculate what percentage a number is of another number, divide the part by the whole and multiply by 100.
Examples:
30 is what % of 150? = (30 ÷ 150) × 100 = 20%
45 is what % of 180? = (45 ÷ 180) × 100 = 25%
17 is what % of 50? = (17 ÷ 50) × 100 = 34%
How to Find Percentage of a Number on a Calculator
To find percentage of a number on a calculator, use this sequence: enter the number, press ×, enter the percentage, press ÷, enter 100, press =. For example, for 20% of 150: press 150 × 20 ÷ 100 =, which gives 30. On calculators with a % key, you can also press 150 × 20% directly — the % key automatically divides by 100. To get percentage of a number on a calculator for the reverse direction (what % is 30 of 150): press 30 ÷ 150 × 100 = to get 20.
How to Calculate Percentage of a Number in Excel
To calculate percentage of a number in Excel, put the number in A1 and the percentage in B1. Use =A1*B1/100 if B1 contains the number 20 (for 20%). Or use =A1*B1 if B1 is formatted as a percentage cell containing 20%. To find what percentage one number is of another in Excel: if the part is in A1 and the whole in B1, use =A1/B1*100 for the number, or =A1/B1 formatted as a percentage. The Excel formula to calculate percentage of a number works identically in Google Sheets.
How to Calculate 20% of a Number
To calculate 20 percentage of a number, multiply the number by 0.20. Or find 10% first (move decimal left one place) and double it. For example: 20% of 350 = 350 × 0.20 = 70. Or: 10% of 350 = 35, doubled = 70. Both methods give the same result. Use the calculator above for any number — just enter 20 in the percentage field and your number in the second field.
How to Calculate 25% of a Number
To calculate 25 percentage of a number, divide the number by 4 (since 25% = 1/4). For example: 25% of 200 = 200 ÷ 4 = 50. Or multiply by 0.25: 200 × 0.25 = 50. For quick mental calculation of 25% of any whole number, dividing by 4 is usually the fastest method. To work out percentage of a number on calculator, enter 25 in the percentage field above.
Examples — Click to Calculate
Click any example to instantly calculate in the tool above.
Common Percentage of a Number — Quick Reference Table
| Number | 10% | 15% | 20% | 25% | 50% |
|---|---|---|---|---|---|
| 50 | 5 | 7.5 | 10 | 12.5 | 25 |
| 100 | 10 | 15 | 20 | 25 | 50 |
| 150 | 15 | 22.5 | 30 | 37.5 | 75 |
| 200 | 20 | 30 | 40 | 50 | 100 |
| 250 | 25 | 37.5 | 50 | 62.5 | 125 |
| 500 | 50 | 75 | 100 | 125 | 250 |
| 1,000 | 100 | 150 | 200 | 250 | 500 |
Frequently Asked Questions
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