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Fractional inches to millimeters

Convert tape-measure fractions like 3/8 or 1 5/16 inch to millimeters, with the math shown step by step.

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Millimeters
28.58 mm

1 1/8 in = 28.58 mm

Also equals

How it works

mm = in × 25.4

Turn the fraction into a decimal first: divide the top number by the bottom number and add any whole inches. One inch is exactly 25.4 millimeters, so multiply by 25.4.

  1. Turn the fraction into a decimal 1 1/8 in = 1.125 in
  2. Multiply by 25.4 1.125 × 25.4 = 28.58 mm
Picture it

The 1 1/8 in mark is 28.58 mm from the end of the tape.

Nearby values

Inches Millimeters Centimeters Inches
15/16 in 23.81 mm 2.38 0.94
1 in 25.4 mm 2.54 1
1 1/16 in 26.99 mm 2.7 1.06
1 1/8 in 28.58 mm 2.86 1.13
1 3/16 in 30.16 mm 3.02 1.19
1 1/4 in 31.75 mm 3.18 1.25
1 5/16 in 33.34 mm 3.33 1.31

Printed from rocketcalc.io/length/inch-fractions-to-mm/1-1-8