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Woodworking Math

3/16 inch in decimal and mm

Decimal inches

0.1875 in

Millimetres

4.7625 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: 3/16 in = 3 ÷ 16 = 0.1875 in.
  2. An inch is exactly 25.4 mm, so 0.1875 × 25.4 = 4.7625 mm, or 4.763 mm to three places.
  3. In feet, divide by 12: 0.1875 ÷ 12 = 0.015625 ft. In centimetres, divide the mm by 10: 0.47625 cm.
  4. The same size in finer steps: 3/16 = 6/32 = 12/64. A tape marked in 16ths, 32nds or 64ths shows it at those marks.

3/16 to the nearest 1/8

A tape or rule marked more coarsely than 16ths can’t show 3/16 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)
1/81/4 in+0.0625+1.588

Drills, plywood and lumber at 3/16 in

Drills either side of 3/16 in
DrillSizeOff by
4.7 mm0.185 in−0.0625 mm
4.8 mm0.189 in+0.0375 mm

Every drill is on the drill bit size chart.

Bits of this size

Sizes either side

FractionDecimalmm
11/64 in0.171875 in4.366 mm
13/64 in0.203125 in5.159 mm

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