Recipes use fractions, spreadsheets use decimals, and most of us have to switch between them sooner or later. Neither direction is hard, but a few fractions never end.
Fraction to decimal
Divide the numerator by the denominator. 3/8 is 3 ÷ 8 = 0.375. 1/4 is 0.25 and 7/10 is 0.7. These all end (they “terminate”). A fraction terminates only when, in lowest terms, its denominator has no prime factors other than 2 and 5.
Others repeat forever. 1/3 is 0.3333… and 1/7 is 0.142857142857…. The calculator shows 1/3 as 0.33333333, rounded to a fixed number of places, so treat a long run of 3s as “one third” rather than an exact value.
Decimal to fraction
Write the digits over a power of ten, then simplify. 0.125 is 125/1000, which divides by 125 to give 1/8. 0.35 is 35/100, which simplifies to 7/20. The more digits after the point, the larger the power of ten you start from.
Using the converter
- Pick the direction: fraction to decimal, or decimal to fraction.
- For a fraction, enter the numerator and denominator. For a decimal, type a plain number such as 0.75 or −3.5.
- Read the result. Fractions come back in lowest terms.
A denominator of zero is rejected, and the decimal field only accepts plain decimal numbers, not percentages or expressions.
Common conversions
| Fraction | Decimal |
|---|---|
| 1/8 | 0.125 |
| 1/5 | 0.2 |
| 3/8 | 0.375 |
| 2/3 | 0.6667 (repeating) |
Frequently asked questions
Why is my converted decimal slightly off?
If the fraction repeats, the decimal is rounded. 1/3 cannot be written exactly in decimal form, so keep the fraction when exactness matters.
How do I convert a mixed number such as 2 3/4?
Convert the fractional part (3/4 = 0.75) and add the whole number, giving 2.75.