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Woodworking Math

15/64 inch in decimal and mm

Decimal inches

0.234375 in

0.2344 in to four places

Millimetres

5.953125 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: 15/64 in = 15 ÷ 64 = 0.234375 in.
  2. An inch is exactly 25.4 mm, so 0.234375 × 25.4 = 5.953125 mm, or 5.953 mm to three places.
  3. In feet, divide by 12: 0.234375 ÷ 12 = 0.019531 ft. In centimetres, divide the mm by 10: 0.5953125 cm.

15/64 to the nearest 1/8, 1/16, 1/32

A tape or rule marked more coarsely than 64ths can’t show 15/64 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)
1/81/4 in+0.015625+0.397
1/161/4 in+0.015625+0.397
1/321/4 in+0.015625+0.397

Drills, plywood and lumber at 15/64 in

Drills either side of 15/64 in
DrillSizeOff by
5.9 mm0.2323 in−0.0531 mm
6 mm0.2362 in+0.0469 mm

Every drill is on the drill bit size chart.

Bits of this size

Sizes either side

FractionDecimalmm
7/32 in0.21875 in5.556 mm
1/4 in0.25 in6.350 mm

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