Decimal to Fraction Converter

How to use

1. 1Type a decimal like 0.625 or a fraction like 5/8 into the input. The tool detects which direction to convert.
2. 2Use a preset chip to try common examples (0.625, 1/3, 22/7, 1 3/4).
3. 3For decimals, pick a precision: Exact keeps every digit; Best fit caps the denominator so 0.333333 becomes 1/3 instead of 333333/1000000.
4. 4Read the result card for the simplified fraction or the decimal expansion. Repeating decimals are shown with the period in parentheses.
5. 5When converting a decimal, the nearest standard fraction table maps your value to common imperial denominators (down to 1/64) with the rounding error shown.
6. 6Click Copy report to copy a plain-text summary with every form (exact, mixed, decimal, percent, inch fractions).

About this tool

Decimal to Fraction Converter is a two-way converter between decimals and fractions, built around the kind of conversion students, machinists, woodworkers, cooks, and engineers actually search for. Type 0.625 and you get 5/8 in lowest terms; type 5/8 and you get 0.625. Type 1/3 and you get 0.(3), the repeating-block notation used in US textbooks. The math runs on BigInt internally so digits are never lost to floating-point rounding. Two algorithms do the work: decimal-to-fraction uses an Exact mode (typed digits over a power of ten, reduced by the greatest common divisor) and a Best fit mode that runs the continued-fraction expansion under a chosen maximum denominator, which is the same algorithm behind Python's Fraction.limit_denominator and NumPy's Rational helpers; fraction-to-decimal uses long division with cycle detection over BigInts so terminating decimals stop cleanly and repeating decimals report the exact period (1/7 returns 0.(142857) with a six-digit cycle). The tool also produces a nearest standard fraction table to the common imperial denominators stamped on US tape measures and drill-bit sets (1/2, 1/4, 1/8, 1/16, 1/32, 1/64) with the rounding error shown next to each row, so a 0.218 reading from a caliper rounds to 7/32 with a known gap. Mixed numbers are supported in both directions: 1 3/4 parses as one and three quarters, and 7/4 returns 1 3/4 as the mixed form alongside the improper fraction. A percent form is included for school answers and recipes. The tool detects when the typed decimal looks like a repeating pattern (three or more clean repetitions of the trailing digits) and surfaces the corresponding exact fraction, which solves the common problem of getting 333333/1000000 instead of 1/3 from a typed 0.333333. Direction is auto-detected from the input: a slash means fraction, a dot or a bare integer means decimal. Useful for homework, for converting a dial reading to a clean fraction on a shop floor, for sizing parts to imperial drill bits, for translating recipe scalings between forms, and for any time the answer needs to be expressed as a clean rational rather than a rounded decimal. All math runs in your browser. The numbers you type are never uploaded, logged, or sent to a server.

Free to use. Works in your browser. No signup, no login.