How to convert fractions to decimals is mostly about dividing: the decimal value of a fraction is its numerator divided by its denominator. Mixed numbers first become improper fractions, then you divide. This guide also covers the important edge case: some fractions produce repeating decimals, so you may need a rounding policy.
For instant conversion in your browser, use Decimal ↔ fraction.
Key takeaways
- Fraction-to-decimal: compute
numerator / denominator. - Mixed numbers convert to improper fractions before dividing.
- Simplifying first can make repeating decimals easier to spot.
- Repeating decimals need a rounding or truncation decision.
Step-by-step: simple proper fractions
Example: convert 3/8.
- Divide 3 by 8.
- Write the decimal result.
- Round to the digits you need (or keep exact if it terminates).
3/8 = 0.375.
Mixed numbers: convert first, then divide
Mixed number form looks like a b/c (a whole number plus a fraction). Convert it to an improper fraction: (a * c + b) / c, then divide.
Example: 2 1/8.
Improper fraction: (2*8 + 1)/8 = 17/8.
Decimal: 17/8 = 2.125.
What about repeating decimals?
Some fractions do not terminate and instead produce repeating decimals. For example, 1/3 = 0.333.... In practice, you usually round to a set number of decimal places.
Best practices
- If you need a decimal for comparison or input fields, decide the number of decimal places up front (for example 2, 3, or 6).
- If you need exact arithmetic, keep the fraction form rather than rounding.
- If you want simplest decimals that come from simpler fractions, simplify the fraction first (divide by the greatest common divisor).
Next: convert decimals back to fractions
If you want the reverse conversion, see how to convert decimal to fraction.
Reference
For a walkthrough of converting fractions to decimals, see Maths Is Fun: Convert Fractions to Decimals.