How Many mm Is 1/2 Inch?

Answer
12.7 mm = 1/2 inch

0.5 × 25.4 = 12.7 mm, exactly. The closest metric sizes are 12 mm and 13 mm; a 13 mm wrench fits a 1/2″ bolt head loosely. A 1/2-inch pipe is a nominal size: its outside diameter is 0.840 in (21.3 mm).

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    Fractional inches to mm

    InchDecimalmm
    1/8″0.1253.175 mm
    1/4″0.256.35 mm
    3/8″0.3759.525 mm
    1/2″0.512.7 mm
    5/8″0.62515.875 mm
    3/4″0.7519.05 mm
    7/8″0.87522.225 mm
    1″125.4 mm
    1 1/4″1.2531.75 mm
    1 1/2″1.538.1 mm
    2″250.8 mm

    Inch fractions are exact in mm because 1 in = 25.4 mm exactly.

    Frequently asked questions

    Is 12 mm the same as 1/2 inch?

    No: 1/2″ = 12.7 mm. 12 mm = 0.472 in, just under 1/2″.

    What is 1/4 inch in mm?

    1/4″ = 6.35 mm.

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