How to use
- Type the decimal. For a repeating decimal, put the repeating digits in brackets: 0.(3) means 0.333… and 0.1(6) means 0.1666…
- Choose the answer you want: the exact fraction, the nearest 1/16 (or 1/8, 1/64…), or the simplest fraction with a denominator up to a limit.
- Read the fraction, the mixed number and the step-by-step working.
How decimal to fraction conversion works
Terminating decimals: write the digits over 10, 100, 1000 and so on, one zero per decimal place. Then divide the top and bottom by their greatest common divisor (GCD).
Repeating decimals: call the number x, multiply by a power of 10 to line up the repeating part, and subtract so the repeat cancels. Then solve for x.
Nearest fraction: for a ruler, multiply by 16 (or 8, 32, 64), round to a whole number, and put it over 16. The “simplest fraction” option instead finds the closest fraction whose denominator stays under your limit.
Examples
- 2.375: 2375/1000, and the GCD is 125, so 19/8, or 2 3/8 as a mixed number.
- 0.1(6): 100x = 16.(6) and 10x = 1.(6). Subtracting gives 90x = 15, so x = 15/90 = 1/6.
- 3.(26): 100x − x = 326.(26) − 3.(26), so 99x = 323 and x = 323/99.
- 0.3 inch to the nearest 1/16: 0.3 × 16 = 4.8, which rounds to 5, so about 5/16 inch (0.0125 too long).
- 3.14159265358979 with denominators up to 1,000: the closest fraction is 355/113.
Common decimals as fractions
| Decimal | Fraction | Nearest 1/16 |
|---|---|---|
| 0.125 | 1/8 | 1/8 |
| 0.2 | 1/5 | 3/16 |
| 0.25 | 1/4 | 1/4 |
| 0.3 | 3/10 | 5/16 |
| 0.(3) | 1/3 | 5/16 |
| 0.375 | 3/8 | 3/8 |
| 0.5 | 1/2 | 1/2 |
| 0.625 | 5/8 | 5/8 |
| 0.(6) | 2/3 | 11/16 |
| 0.75 | 3/4 | 3/4 |
| 0.875 | 7/8 | 7/8 |
0.333 versus 0.(3), and 0.999…
A decimal that stops is exact: 0.333 is 333/1000, not 1/3. Only the endlessly repeating 0.333… equals 1/3, so type it as 0.(3). The calculator suggests the bracket form when your digits look like a cut-off repeat.
A repeating 9 equals the next value up: 0.(9) = 1, because 10x − x = 9 gives x = 1.
To add or multiply the fractions you get, use the fraction calculator.