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Woodworking Math

7/64 inch in decimal and mm

Decimal inches

0.109375 in

0.1094 in to four places

Millimetres

2.778125 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: 7/64 in = 7 ÷ 64 = 0.109375 in.
  2. An inch is exactly 25.4 mm, so 0.109375 × 25.4 = 2.778125 mm, or 2.778 mm to three places.
  3. In feet, divide by 12: 0.109375 ÷ 12 = 0.009115 ft. In centimetres, divide the mm by 10: 0.2778125 cm.

7/64 to the nearest 1/8, 1/16, 1/32

A tape or rule marked more coarsely than 64ths can’t show 7/64 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)
1/81/8 in+0.015625+0.397
1/161/8 in+0.015625+0.397
1/321/8 in+0.015625+0.397

Drills, plywood and lumber at 7/64 in

Drills either side of 7/64 in
DrillSizeOff by
2.7 mm0.1063 in−0.0781 mm
2.8 mm0.1102 in+0.0219 mm

Every drill is on the drill bit size chart.

Bits of this size

Sizes either side

FractionDecimalmm
3/32 in0.09375 in2.381 mm
1/8 in0.125 in3.175 mm

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