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Woodworking Math

1-3/16 inch in decimal and mm

Decimal inches

1.1875 in

Millimetres

30.1625 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: 1-3/16 in = 1 + 3 ÷ 16 = 1.1875 in.
  2. An inch is exactly 25.4 mm, so 1.1875 × 25.4 = 30.1625 mm, or 30.163 mm to three places.
  3. In feet, divide by 12: 1.1875 ÷ 12 = 0.098958 ft. In centimetres, divide the mm by 10: 3.01625 cm.
  4. The same size in finer steps: 1-3/16 = 1-6/32 = 1-12/64. A tape marked in 16ths, 32nds or 64ths shows it at those marks.

1-3/16 to the nearest 1/8

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

Drills, plywood and lumber at 1-3/16 in

No drill, plywood or lumber on our charts is exactly 1-3/16 in. The nearest drills are below.

Drills either side of 1-3/16 in
DrillSizeOff by
1 in1 in−0.1875 in
25 mm0.9843 in−5.1625 mm

Every drill is on the drill bit size chart.

Sizes either side

FractionDecimalmm
1-1/8 in1.125 in28.575 mm
1-1/4 in1.25 in31.750 mm

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