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Woodworking Math

3/64 inch in decimal and mm

Decimal inches

0.046875 in

0.0469 in to four places

Millimetres

1.190625 mm

From the standard, the international inch, 25.4 mm exactly

The math

  1. A fraction is its top number divided by its bottom number: 3/64 in = 3 ÷ 64 = 0.046875 in.
  2. An inch is exactly 25.4 mm, so 0.046875 × 25.4 = 1.190625 mm, or 1.191 mm to three places.
  3. In feet, divide by 12: 0.046875 ÷ 12 = 0.003906 ft. In centimetres, divide the mm by 10: 0.1190625 cm.

3/64 to the nearest 1/8, 1/16, 1/32

A tape or rule marked more coarsely than 64ths can’t show 3/64 exactly. The nearest marks, and how far off each is (plus means the mark is bigger; a size exactly halfway goes to the bigger mark):

NearestMarkOff by (in)Off by (mm)
1/80 in−0.046875−1.191
1/161/16 in+0.015625+0.397
1/321/16 in+0.015625+0.397

Drills, plywood and lumber at 3/64 in

Drills either side of 3/64 in
DrillSizeOff by
1.1 mm0.0433 in−0.0906 mm
1.2 mm0.0472 in+0.0094 mm

Every drill is on the drill bit size chart.

Sizes either side

FractionDecimalmm
1/32 in0.03125 in0.794 mm
1/16 in0.0625 in1.588 mm

Every size is on the fraction to decimal chart; any other size goes in the fraction to decimal calculator.