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Woodworking Math

31/32 inch in decimal and mm

Decimal inches

0.96875 in

0.9688 in to four places

Millimetres

24.60625 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: 31/32 in = 31 ÷ 32 = 0.96875 in.
  2. An inch is exactly 25.4 mm, so 0.96875 × 25.4 = 24.60625 mm, or 24.606 mm to three places.
  3. In feet, divide by 12: 0.96875 ÷ 12 = 0.080729 ft. In centimetres, divide the mm by 10: 2.460625 cm.
  4. The same size in finer steps: 31/32 = 62/64. A tape marked in 16ths, 32nds or 64ths shows it at those marks.

31/32 to the nearest 1/8, 1/16

A tape or rule marked more coarsely than 32ths can’t show 31/32 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 in+0.03125+0.794
1/161 in+0.03125+0.794

Drills, plywood and lumber at 31/32 in

Drills either side of 31/32 in
DrillSizeOff by
24.5 mm0.9646 in−0.1062 mm
25 mm0.9843 in+0.3938 mm

Every drill is on the drill bit size chart.

Bits of this size

Sizes either side

FractionDecimalmm
61/64 in0.953125 in24.209 mm
63/64 in0.984375 in25.003 mm

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