Exact math and number tool

Decimal to Fraction Calculator

Convert a terminating decimal into an exact simplified fraction. The typed decimal string—not JavaScript binary floating point—is the source of truth, so 0.1 becomes 1/10.

Enter values and select Calculate.

How to use this calculator

  1. Enter a terminating decimal with no more than 15 decimal places.
  2. Select Calculate to see the simplified and improper fraction forms.
  3. Use the mixed-number form when a value greater than one is easier to read that way.
  4. Copy only the displayed calculation result when needed.

Formula and method

Digits after the decimal determine a power-of-ten denominator. The resulting integer numerator and denominator are reduced by their greatest common factor.

Worked example

For 2.75, remove the decimal to get 275/100, reduce to 11/4, and display the mixed number 2 3/4.

Assumptions and limits

  • Typed decimal digits represent an exact terminating decimal.
  • A string such as 0.333333 is not inferred to mean one third.
  • Explicit repeating notation is deferred rather than guessed.
  • Integers and negative decimals are accepted.

Understanding the result

The result follows the displayed deterministic method. Exact-integer operations use BigInt where appropriate, and any controlled precision limit is stated before the related output can be interpreted.

Common mistakes

  • Expecting a rounded decimal to be treated as an exact repeating value
  • Entering commas, expressions, or multiple decimal points
  • Confusing a mixed number with multiplication
  • Using more than the documented 15 decimal places

Methodology note

The calculator uses the arithmetic definitions shown on this page. It does not call an external calculator service, evaluate expressions, or infer unselected mathematical conventions.

This deterministic utility is a calculation aid. Confirm required notation, precision, and course or professional conventions separately.