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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 1/8 in

28.58 mm ≈ 1 1/8 in

Exact size 1.125 in · 1 1/8 in is 0.01 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 28.58 ÷ 25.4 = 1.1252 in
  2. Count the 1/16 in marks 1.1252 × 16 = 18 → nearest mark: 18
  3. Simplify the fraction 18/16 in = 1 1/8 in
Picture it

28.58 mm is 1.125 in, between marks. The nearest mark is 1 1/8 in (0.01 mm under).

Nearest mark Exact size

Nearby values

Millimeters Inches (fraction) Exact Centimeters
25.58 mm 1 in 1.01 2.56
26.58 mm 1 1/16 in 1.05 2.66
27.58 mm 1 1/16 in 1.09 2.76
28.58 mm 1 1/8 in 1.13 2.86
29.58 mm 1 3/16 in 1.16 2.96
30.58 mm 1 3/16 in 1.2 3.06
31.58 mm 1 1/4 in 1.24 3.16

Printed from rocketcalc.io/length/mm-to-inch-fractions/28.58