FractionFractions made useful.
Type what you have: 3/8, 1 3/4, 0.375, 37.5%, 10 mm, 25/64". You get the exact answer
first — and when the question is a real measurement, the simplest fraction that fits it.
Try:
Start with the question you have
Look up What is this fraction? 3/8 = 0.375 = 37.5%
Every everyday fraction has a permanent page: exact decimal, percent, equivalent
fractions, the bar model, and what it measures in millimetres.
Convert Turn a decimal or percent back into a fraction. 0.625 = 5/8 = 62.5%
Decimal ↔ fraction ↔ percent, exactly — including repeating decimals like 0.(3),
which most converters silently truncate.
Match What is 10 mm on my tape measure?
10 mm → 25/64" (−0.0781 mm off)
Metric to fractional inches with the nearest 16th, 32nd and 64th, each with its exact
signed error — 1 inch = 25.4 mm by definition, never approximated.
Fit What is the simplest fraction that fits?
10 mm ± 0.5 mm → 3/8" = 9.525 mm
Give a target and a tolerance, get the simplest fraction inside it — ranked by a
documented rule, with every qualifying alternative, or an honest “nothing fits.”
The rest of the toolkit
Simplify 24/64 → 3/8, with the GCD shown when you want it. Equivalent fractions 3/8 = 6/16 = 9/24, or rewrite over the denominator you need. Add, subtract, multiply, divide Exact fraction arithmetic with optional steps. Compare fractions Which is larger, by cross multiplication — never by float. Compare measurements 5/16" vs 8 mm: both units, exact difference, which is larger. Mixed ↔ improper 1 3/4 ↔ 7/4, both directions. Printable charts Fraction–decimal, fraction–metric, 16ths through 128ths. The ruler Every fraction of an inch in its place, tap any mark. Rational approximation 3.14159 → 22/7, 355/113, each with its error.
Somewhere to start
1/2 = 0.5 1/3 ≈ 0.3333 2/3 ≈ 0.6667 1/4 = 0.25 3/4 = 0.75 3/8 = 0.375 5/8 = 0.625 7/8 = 0.875 3/16 = 0.1875 5/16 = 0.3125 13/32 ≈ 0.4063 25/64 ≈ 0.3906
What this site will not do
- Guess. An input it cannot parse comes back as an error saying what is wrong with it, not as the nearest thing it could make out of the characters. 0.333 is 333/1000; only 0.(3) is 1/3, and the difference is yours to state.
- Round silently. Exact values print as equalities; rounded ones are marked. 3/8 = 0.375, but 1/3 ≈ 0.3333 — and the page says which is which, every time.
- Force a fit. When no fraction in your denominator set falls inside the tolerance, the matcher says so. An answer that misses the tolerance is worse than knowing nothing fits.
- Use floating point where it counts. Fractions are pairs of integers end to end. Comparisons cross-multiply, errors are exact, and 25.4 mm to the inch is a definition, not an approximation.