The calculation, without hidden assumptions
Tape measures and many fabrication drawings use binary inch fractions such as 1/8, 1/16, 1/32 and 1/64. This calculator lets you choose that precision instead of silently deciding it, then reports the rounded mark and the rounding error so you can see what precision was lost.
How to use this calculator
Choose decimal inches, millimeters or fraction-to-decimal mode.
Select the tape-measure precision you actually need, from halves through sixty-fourths.
Read the nearest simplified fraction, feet-and-inches form, metric equivalent and signed rounding error.
Where people use it
- •Reading tape-measure dimensions
- •Woodworking and fabrication
- •Converting metric drawing dimensions to practical inch marks
Example: 2.695 in to nearest 1/32
The fractional part is multiplied by 32 and rounded to the nearest mark. The result is then simplified if the numerator and denominator share a factor, and the error from 2.695 in is shown.
What the result does not assume
- •Rounding to a ruler mark intentionally changes the value. Use the error display to decide whether the chosen denominator is precise enough.
- •Do not use rounded construction fractions where a drawing, machining process or tolerance requires the original decimal/metric dimension.
Frequently asked questions
Why can a 1/64 result simplify to 1/16?+
If the rounded numerator and denominator share a common factor, the fraction is reduced without changing the selected mark.
How many millimeters are in one inch?+
Exactly 25.4 mm equal one inch.
Can I get feet and inches too?+
Yes. Decimal-inch inputs are also split into whole feet plus remaining fractional inches.
Semantic next steps
Continue the calculation
These links move to a different input, formula or project stage rather than a keyword variation of this page.
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Keep the result connected to the real job
MAXScanner keeps the formula and assumptions beside the result so you can verify the number before using it in a drawing, estimate, specification, worksheet or document. Where a supplier, manufacturer, drawing or applicable standard owns a requirement, that source remains authoritative.