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Woodworking Math

15/32 inch in decimal and mm

Decimal inches

0.46875 in

0.4688 in to four places

Millimetres

11.90625 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: 15/32 in = 15 ÷ 32 = 0.46875 in.
  2. An inch is exactly 25.4 mm, so 0.46875 × 25.4 = 11.90625 mm, or 11.906 mm to three places.
  3. In feet, divide by 12: 0.46875 ÷ 12 = 0.039063 ft. In centimetres, divide the mm by 10: 1.190625 cm.
  4. The same size in finer steps: 15/32 = 30/64. A tape marked in 16ths, 32nds or 64ths shows it at those marks.

15/32 to the nearest 1/8, 1/16

A tape or rule marked more coarsely than 32ths can’t show 15/32 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)
1/81/2 in+0.03125+0.794
1/161/2 in+0.03125+0.794

Drills, plywood and lumber at 15/32 in

Drills either side of 15/32 in
DrillSizeOff by
11.9 mm0.4685 in−0.0062 mm
12 mm0.4724 in+0.0938 mm

Every drill is on the drill bit size chart.

Bits of this size

Sizes either side

FractionDecimalmm
29/64 in0.453125 in11.509 mm
31/64 in0.484375 in12.303 mm

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