Decimal to Fraction Calculator
Every terminating decimal is a fraction with a power of ten underneath. 0.375 is 375 thousandths, which reduces to 3/8. This calculator writes the decimal over the right power of ten, reduces it with the greatest common factor, and also offers the closest simple fraction when you paste a rounded decimal such as 0.333333.
How to use the decimal to fraction calculator
- Type the decimal number, for example 0.625 or 2.5.
- Read the fraction in lowest terms and the mixed number if the value is above 1.
- If the decimal looks like a rounded repeating value, check the “closest simple fraction” line.
Formula
Count the decimal places k, write the digits over 10k, then divide both parts by their GCF. Example: 0.375 = 375/1000 = 3/8 because GCF(375, 1000) = 125.
Worked examples
A terminating decimal
0.125 has 3 decimal places, so it is 125/1000. The GCF is 125, giving 1/8.
A mixed number
2.5 = 25/10 = 5/2, which is the mixed number 2 1/2.
Common decimal and fraction equivalents
| Decimal | Fraction | Percent |
|---|---|---|
| 0.125 | 1/8 | 12.5% |
| 0.2 | 1/5 | 20% |
| 0.25 | 1/4 | 25% |
| 0.333… | 1/3 | 33.3% |
| 0.375 | 3/8 | 37.5% |
| 0.5 | 1/2 | 50% |
| 0.666… | 2/3 | 66.7% |
| 0.75 | 3/4 | 75% |
Why some decimals never end
A fraction in lowest terms gives a terminating decimal only when its denominator’s prime factors are just 2 and 5, the primes that divide 10. So 3/8 (8 = 2³) ends at 0.375, but 1/3 and 1/7 repeat forever. That is why 0.333333 is only an approximation of 1/3.
Tips for measuring
Rulers, wrenches and recipes use fractions such as 5/16 and 3/8, but digital tools show decimals. Converting 0.3125 gives 5/16, which is exactly what you need to pick the right drill bit or spanner. Denominators of 2, 4, 8, 16 and 32 are the usual choices for imperial tools.
Check your work
Divide the numerator by the denominator on a calculator. If you get your original decimal back, the fraction is right. You can also use the fraction calculator to add or compare the results.
Practice problems
Try these yourself first, then check your answer. The answers come from the calculator above.
- Write 0.85 as a fraction.
Show answer
Fraction (lowest terms): 17/20
- Write 3.125 as a fraction.
Show answer
Fraction (lowest terms): 25/8
Common mistakes to avoid
- Expecting an exact answer for a rounded decimal. 0.333333 is exactly 333333/1000000; the friendly answer 1/3 is an approximation.
- Forgetting to simplify. 50/100 and 1/2 are equal, but 1/2 is the standard form.
Frequently asked questions
How do you convert a decimal to a fraction?
Write the digits over 1 followed by as many zeros as there are decimal places, then simplify.
How do I convert a repeating decimal?
For 0.333… let x = 0.333…, so 10x = 3.333… Subtract to get 9x = 3, so x = 1/3. This tool shows the closest simple fraction for long decimals.
What is 0.75 as a fraction?
75/100, which simplifies to 3/4.
Can negative decimals be converted?
Yes. The sign carries over: −0.75 = −3/4.
Reviewed September 26, 2026 by the SolveCalcPro editorial team. Found a mistake? Tell us; see our editorial policy.