Percent of a Number Calculator
Type a percentage and a number to get that share of it, worked out step by step, with a bar showing the part against the whole.
What is % of ?
15% of 240
36
15% of 240 is 36.
How this works: Method, 2 sources, Checked against 2 worked examples,
How this works
Method
A percentage is a number of hundredths: 15% means 15 out of every 100. To take 15% of something, turn the percentage into a decimal by dividing by 100 (15 ÷ 100 = 0.15) and multiply the number by it. For 15% of 240 that is 0.15 × 240 = 36. Full method
Sources
How it’s tested
2 worked examples for this page are checked by automated tests before every release: given the inputs, the tool must show the expected answer.
Privacy
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Changes
- Added eight pages for common questions, from percent of a number to percent error and reverse percentages, each with its own method, examples and table.
- Added key facts with a worked example of each formula.
- Redesigned: type the numbers straight into a sentence, with bars on one scale that picture the answer.
- Results now update as you type, with no Calculate button.
- First published.
How to find a percentage of a number
A percentage is a number of hundredths: 15% means 15 out of every 100. To take 15% of something, turn the percentage into a decimal by dividing by 100 (15 ÷ 100 = 0.15) and multiply the number by it. For 15% of 240 that is 0.15 × 240 = 36.
Multiplication works in either order, which gives a handy shortcut: X% of Y is always the same as Y% of X. So 8% of 50 is the same as 50% of 8, which is 4, and 4% of 75 equals 75% of 4, which is 3.
For mental maths, build from 10% and 1%. Moving the decimal point one place left gives 10% (10% of 240 is 24), half of that is 5% (12), and adding them gives 15% (36). The same trick handles a 20% tip: double the 10%.
X% of Y = X ÷ 100 × Y
- The word comes from the Latin “per centum”, meaning “by the hundred”. Source: Online Etymology Dictionary, percent.
- US schools teach this in grade 6 as finding “a percent of a quantity as a rate per 100”, for example 30% of a quantity means 30/100 times the quantity. Source: Common Core State Standards, Grade 6 Ratios and Proportional Relationships (6.RP.A.3c).
Common percentages as fractions and decimals
Each percentage with its fraction and decimal, and what it is of 80 and of 250, worked out exactly.
| Percent | Fraction | Decimal | Of 80 | Of 250 |
|---|---|---|---|---|
| 1% | 1/100 | 0.01 | 0.8 | 2.5 |
| 5% | 1/20 | 0.05 | 4 | 12.5 |
| 10% | 1/10 | 0.1 | 8 | 25 |
| 12.5% | 1/8 | 0.125 | 10 | 31.25 |
| 15% | 3/20 | 0.15 | 12 | 37.5 |
| 20% | 1/5 | 0.2 | 16 | 50 |
| 25% | 1/4 | 0.25 | 20 | 62.5 |
| 33⅓% | 1/3 | 0.3333 | 26.67 | 83.33 |
| 40% | 2/5 | 0.4 | 32 | 100 |
| 50% | 1/2 | 0.5 | 40 | 125 |
Show all 18 rowsShow fewer
| 60% | 3/5 | 0.6 | 48 | 150 |
| 66⅔% | 2/3 | 0.6667 | 53.33 | 166.67 |
| 75% | 3/4 | 0.75 | 60 | 187.5 |
| 80% | 4/5 | 0.8 | 64 | 200 |
| 90% | 9/10 | 0.9 | 72 | 225 |
| 100% | 1 | 1 | 80 | 250 |
| 150% | 3/2 | 1.5 | 120 | 375 |
| 200% | 2 | 2 | 160 | 500 |
Frequently Asked Questions
What is 20% of 50?
20% of 50 is 10: 20 ÷ 100 = 0.2, and 0.2 × 50 = 10. Or find 10% (5) and double it.
How do I work out a 15% tip?
Take 10% of the bill by moving the decimal point one place left, then add half of that. On a $64 bill, 10% is $6.40 and 5% is $3.20, so a 15% tip is $9.60.
Can a percentage be more than 100%?
Yes. 150% of 40 is 1.5 × 40 = 60, more than the number you started with. Anything above 100% is more than the whole.
Is X% of Y the same as Y% of X?
Always, because both are X × Y ÷ 100. Swapping can make a sum easy: 4% of 25 is 25% of 4, which is 1.