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Millimeters to fractional inches

Convert millimeters to the nearest 1/16, 1/32 or 1/64 inch, like the marks on a tape measure, with the math shown step by step.

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Inches (fraction)
1/2 in

12.88 mm ≈ 1/2 in

Exact size 0.507 in · 1/2 in is 0.18 mm under

Also equals

How it works

in = mm ÷ 25.4

One inch is exactly 25.4 millimeters, so dividing by 25.4 gives inches as a decimal. To read that on a tape measure, count how many 1/16-inch marks it covers, round to the nearest mark, then simplify the fraction.

  1. Divide by 25.4 to get inches 12.88 ÷ 25.4 = 0.5071 in
  2. Count the 1/16 in marks 0.5071 × 16 = 8.11 → nearest mark: 8
  3. Simplify the fraction 8/16 in = 1/2 in
Picture it

12.88 mm is 0.507 in, between marks. The nearest mark is 1/2 in (0.18 mm under).

Nearest mark Exact size

Nearby values

Millimeters Inches (fraction) Exact Centimeters
9.88 mm 3/8 in 0.39 0.99
10.88 mm 7/16 in 0.43 1.09
11.88 mm 7/16 in 0.47 1.19
12.88 mm 1/2 in 0.51 1.29
13.88 mm 9/16 in 0.55 1.39
14.88 mm 9/16 in 0.59 1.49
15.88 mm 5/8 in 0.63 1.59

Printed from rocketcalc.io/length/mm-to-inch-fractions/12.88