1/3 as a decimal is 0.333333… and 1/3 as a percent is 33⅓% (about 33.33% when rounded). To convert, divide 1 by 3 to get the decimal, then multiply by 100 to get the percent. This page shows both conversions step by step, a diagram of 1/3, the full table of thirds, real-life examples and practice problems with answers.
In this guide
1/3 as a Decimal and Percent: Quick Answer
| Form | Value |
|---|---|
| Fraction | 1/3 (one third) |
| Decimal | 0.333333… (rounded: 0.3333) |
| Percent | 33⅓% (rounded: 33.33%) |
| Decimal type | Repeating |
| Simplest form | Yes, 1/3 is already in simplest form |
What Does 1/3 Mean?
The fraction 1/3, read as “one third”, means one of three equal parts, such as one slice of a cake cut into three, or one month of a three-month quarter.
The top number, 1, is the numerator: how many parts you have. The bottom number, 3, is the denominator: how many equal parts make one whole. A fraction bar also means “divided by”, so 1/3 is the same as 1 ÷ 3. That is the key to converting it.
How to Convert 1/3 to a Decimal
Method 1: Divide the numerator by the denominator
Divide 1 by 3. Because 1 is smaller than 3, the answer starts with 0 and a decimal point, and you bring down zeros:
- 10 ÷ 3 = 3, remainder 1
The remainder starts repeating, so the digits 3 repeat forever: 1/3 = 0.333333…. Rounded to four decimal places, that is 0.3333.
Method 2: Make the denominator a power of 10
This shortcut does not work for 1/3. The denominator 3 is a prime number other than 2 or 5, so no whole number turns it into 10, 100 or 1000. That is exactly why 1/3 gives a repeating decimal instead of one that stops. Use division instead.
In short: Divide 1 by 3. 1/3 = 0.333333…, a repeating decimal (about 0.3333).
How to Convert 1/3 to a Percent
Method 1: Convert to a decimal, then multiply by 100
Take the decimal and multiply by 100, which moves the decimal point two places to the right: 0.3333 × 100 = 33.33% (rounded). The exact value is 33⅓%.
Method 2: Multiply by 100 first, then divide
Multiply the numerator by 100 and divide by the denominator: 1 × 100 = 100, and 100 ÷ 3 = 33⅓%.
Method 3: Use the value of one part
Each 1/3 is worth 33⅓%. You have 1 of those parts, so 1/3 = 1 × 33⅓% = 33⅓%. This is the fastest way to work out any fraction with a denominator of 3 in your head.
In short: Multiply 1/3 by 100: 1/3 = 33⅓%. Round to 33.33% if you need a decimal percent.
All Thirds as Decimals and Percents
These are the fractions with a denominator of 3. Learning the whole row makes 1/3 easier to remember, because each one is 33⅓% more than the one before.
| Fraction | Decimal | Percent |
|---|---|---|
| 1/3 | 0.333333… | 33⅓% |
| 2/3 | 0.666666… | 66⅔% |
| 3/3 = 1 | 1 | 100% |
Related conversions: 1/4 as a percent and decimal, 1/2 as a percent and decimal.
How to Use 1/3 in Real Life
Example: Find 1/3 of 18. Divide by 3, then multiply by 1: 18 ÷ 3 = 6, and 6 × 1 = 6.
Example: Find 33⅓% of 90. It is the same as 1/3 of 90: 90 ÷ 3 × 1 = 30.
- Splitting a bill: a $45 bill shared by three people is $15 each, which is 1/3 or 33⅓% of the total.
- Time: 20 minutes is 1/3 of an hour.
- Cooking: 1/3 cup is about 0.33 cup, or 5 tablespoons plus 1 teaspoon.
To find any fraction of a number, divide by the bottom number and multiply by the top. For other percentage problems, see how to calculate a percentage.
Is 1/3 More Than Half?
No. 1/3 = 33⅓%, which is less than 50%. The part that is left over is 2/3, which is 66⅔%, because 33⅓% + 66⅔% = 100%.
How to Convert the Decimal or Percent Back to 1/3
A repeating decimal can be turned back into a fraction with a little algebra. Let x = 0.333333…
- Multiply by 10 to move one full repeating block past the decimal point: 10x = 3.333333…
- Subtract x from both sides so the repeating tails cancel: 9x = 3
- Divide: x = 3/9, which simplifies (÷ 3) to 1/3.
Check with the percent: 1 × 100 ÷ 3 = 33⅓, so 33⅓% is the same as 1/3.
Equivalent fractions of 1/3: 2/6, 3/9, 4/12 and 5/15. They all equal 0.333333… and 33⅓%.
Common Mistakes When Converting 1/3
- Treating 0.33 as exact. 3 × 0.33 = 0.99, not 1. Keep 1/3 as a fraction, or write 0.333… or 33⅓%, until the final step.
- Dividing the wrong way round. 1/3 means 1 ÷ 3, not 3 ÷ 1. 3 ÷ 1 = 3, which is more than 1.
- Forgetting to multiply by 100. 0.3333 is the decimal. The percent is 100 times bigger: 33⅓%.
- Moving the decimal point the wrong way. To go from decimal to percent, move it two places to the right.
1/3 Practice Problems (With Answers)
1. Write 2/3 as a decimal and a percent.
0.666666… and 66⅔%. Divide 2 by 3, then multiply by 100.
2. What is 1/3 of 36?
12. 36 ÷ 3 × 1 = 12.
3. What percent is 7 out of 21?
33⅓%. 7/21 simplifies to 1/3.
4. A tank holds 30 litres and is 1/3 full. How many litres are in it, and what percent full is it?
10 litres, 33⅓% full.
5. Write 66⅔% as a fraction in simplest form.
2/3.
1/3 as a Percent and Decimal: FAQ
What is 1/3 as a decimal?
1/3 as a decimal is 0.333333…, which rounds to 0.3333. Divide 1 by 3 to get it.
What is 1/3 as a percent?
1/3 as a percent is 33⅓%, or about 33.33% when rounded to two decimal places. Multiply the decimal by 100 to get it.
How do you convert 1/3 to a percentage?
Divide 1 by 3 to get 0.3333, then multiply by 100 and add the % sign. Or multiply 1 by 100 first: 100 ÷ 3 = 33⅓%.
Is 1/3 a terminating or repeating decimal?
1/3 is a repeating decimal: the digits 3 repeat forever. This happens because its denominator, 3, has a prime factor other than 2 or 5.
What fractions are equal to 1/3?
2/6, 3/9 and 4/12 are all equal to 1/3, because each is 1/3 with the top and bottom multiplied by the same number.
Sources and Further Reading
- OpenStax, Prealgebra 2e, Section 6.1: Understand Percent, Rice University.
- Math is Fun, Convert Fractions to Decimals.
- Math is Fun, Convert Fractions to Percents.
Every value on this page was checked by exact division. Convert any number with the percentage calculator or the CalcSolver calculator, and browse all percentage and decimal guides.
Related: browse all percentages and decimals guides, or use the equivalent fractions calculator for fractions. See also the equivalent fractions of 1/3.
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