Decimal to Fraction Converter
Turning a Decimal Back into a Ratio
Every terminating or repeating decimal can be rewritten as a fraction of two whole numbers, and doing that conversion by hand means finding the right power of ten and then reducing by the greatest common divisor. This calculator does it in one step, using exact rational arithmetic rather than floating-point approximation, so the fraction it returns is genuinely in lowest terms.
The Formula
The conversion respects a maximum denominator setting (1,000,000 by default), which matters for non-terminating decimals like an approximation of π: the calculator finds the simplest fraction that best represents the input within that denominator limit, rather than an unwieldy exact match.
Where This Conversion Is Used
- Woodworking and machining — converting a decimal measurement from a digital caliper into a fractional inch reading for a standard ruler.
- Cooking — converting a decimal recipe scale factor back into measurable fractional cups or spoons.
- Mathematics coursework — verifying decimal-to-fraction conversions in arithmetic and pre-algebra work.
| Decimal | Fraction |
|---|---|
| 0.75 | 3/4 |
| 0.125 | 1/8 |
| 0.6 | 3/5 |
| 3.14159 | 314159/100000 |
3.14159 isn't a clean fraction because it's a rounded approximation of π, which is irrational and has no exact fractional form.
How to Use This Calculator
- Enter the Decimal Number.
- Optionally enter a Max Denominator to limit how large the resulting fraction's denominator can be (defaults to 1,000,000).
- Select Calculate to see the simplified fraction.
Related Calculations
Need to go the other direction? The Fraction to Decimal Converter handles that, and the Fraction Calculator covers arithmetic on fractions directly.