Decimals come from calculators and digital tools; fractions come from rulers, recipes and woodworking plans. This calculator converts a decimal to an exact fraction in lowest terms and as a mixed number, or — when you need something you can actually measure — to the nearest half, quarter, eighth, sixteenth, thirty-second or sixty-fourth.
How to use the decimal to fraction calculator
- Type the decimal, for example 0.375 or 2.71. Negative numbers work too.
- Choose exact or rounded. “Exact” uses every digit you typed. “Nearest 1/16” and the other options round to a fraction you can find on a tape measure or measuring cup.
- Read the fraction, the mixed number and how far the rounded fraction is from your decimal.
Decimal to fraction formula
Nearest 1/n: numerator = round(decimal × n), fraction = numerator ÷ n, then simplify
d is the number of digits after the decimal point. Simplifying uses the greatest common divisor (GCD), found with Euclid's algorithm.
Worked examples
- 0.375 exactly: 375/1000. GCD is 125, so 3/8.
- 1.6 exactly: 16/10 = 8/5, or 1 3/5 as a mixed number.
- 0.3333 to the nearest 1/16: 0.3333 × 16 = 5.33 → 5/16 (0.3125, about 0.021 under).
- 2.71 to the nearest 1/8: 0.71 × 8 = 5.68 → 6/8 = 3/4, so 2 3/4.
Decimal to fraction chart (sixteenths)
| Decimal | Fraction | Decimal | Fraction |
|---|---|---|---|
| 0.0625 | 1/16 | 0.5625 | 9/16 |
| 0.125 | 1/8 | 0.625 | 5/8 |
| 0.1875 | 3/16 | 0.6875 | 11/16 |
| 0.25 | 1/4 | 0.75 | 3/4 |
| 0.3125 | 5/16 | 0.8125 | 13/16 |
| 0.375 | 3/8 | 0.875 | 7/8 |
| 0.4375 | 7/16 | 0.9375 | 15/16 |
| 0.5 | 1/2 | 1.0 | 1 |
Exact vs. rounded fractions
An exact conversion keeps every digit, which is right for math homework but can produce awkward results — 0.3333 becomes 3333/10000. For practical work you usually want the nearest fraction with a familiar denominator. Woodworkers typically round to 1/16 in, machinists may use 1/64 in or switch to decimal inches, and cooks rarely need finer than 1/8. The “difference” result tells you how much accuracy you give up.
Why fractions still matter
Decimals are convenient on screens, but fractions describe how many physical things are built. Lumber, drill bits, wrenches and pipe fittings in the US are all sized in fractions of an inch, and a tape measure is marked in halves, quarters, eighths and sixteenths. If a plan says 0.4375 in and your drill set is fractional, the match is 7/16. Converting precisely before you cut or buy avoids the drift that creeps in when you round by eye.
Common mistakes
- Misplacing the denominator. 0.05 is 5/100 = 1/20, not 1/5. Count the decimal places carefully.
- Forgetting the whole number. 2.75 is 2 3/4 as a mixed number, or 11/4 as an improper fraction. Both are right.
- Treating a rounded decimal as exact. 0.33 is 33/100, not 1/3.
Tips
- Simplify last. 6/16 and 3/8 are the same; the calculator always reduces to lowest terms.
- Check with division. Divide the numerator by the denominator to confirm you get your decimal back — or use the Fraction to Decimal Calculator.
- Converting measurements? The Unit Converter tool handles inches, feet, centimeters and more.
Frequently asked questions
How do I convert a decimal to a fraction?
Write the decimal over the matching power of 10, then simplify. 0.375 has three decimal places, so it's 375/1000. Dividing top and bottom by 125 gives 3/8.
What is 0.6 as a fraction?
6/10, which simplifies to 3/5.
How do I convert a decimal to the nearest 16th?
Multiply the decimal part by 16, round to the nearest whole number, and put it over 16, then simplify. 0.3333 × 16 = 5.33 → 5/16. Choose “Nearest 1/16” to do this for measurements on a tape.
What about repeating decimals like 0.333…?
A typed decimal always has a finite number of digits, so 0.333 becomes 333/1000. If you mean exactly one third, use the fraction 1/3 — or pick a rounding option to get the nearest simple fraction.
What is 1.25 as a mixed number?
1 1/4. The whole number stays in front and 0.25 becomes 1/4.