Skip to content
Woodworking Math

27/64 inch in decimal and mm

Decimal inches

0.421875 in

0.4219 in to four places

Millimetres

10.715625 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: 27/64 in = 27 ÷ 64 = 0.421875 in.
  2. An inch is exactly 25.4 mm, so 0.421875 × 25.4 = 10.715625 mm, or 10.716 mm to three places.
  3. In feet, divide by 12: 0.421875 ÷ 12 = 0.035156 ft. In centimetres, divide the mm by 10: 1.0715625 cm.

27/64 to the nearest 1/8, 1/16, 1/32

A tape or rule marked more coarsely than 64ths can’t show 27/64 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)
1/83/8 in−0.046875−1.191
1/167/16 in+0.015625+0.397
1/327/16 in+0.015625+0.397

Drills, plywood and lumber at 27/64 in

Drills either side of 27/64 in
DrillSizeOff by
10.7 mm0.4213 in−0.0156 mm
10.8 mm0.4252 in+0.0844 mm

Every drill is on the drill bit size chart.

Bits of this size

Sizes either side

FractionDecimalmm
13/32 in0.40625 in10.319 mm
7/16 in0.4375 in11.113 mm

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