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Woodworking Math

49/64 inch in decimal and mm

Decimal inches

0.765625 in

0.7656 in to four places

Millimetres

19.446875 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: 49/64 in = 49 ÷ 64 = 0.765625 in.
  2. An inch is exactly 25.4 mm, so 0.765625 × 25.4 = 19.446875 mm, or 19.447 mm to three places.
  3. In feet, divide by 12: 0.765625 ÷ 12 = 0.063802 ft. In centimetres, divide the mm by 10: 1.9446875 cm.

49/64 to the nearest 1/8, 1/16, 1/32

A tape or rule marked more coarsely than 64ths can’t show 49/64 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)
1/83/4 in−0.015625−0.397
1/163/4 in−0.015625−0.397
1/3225/32 in+0.015625+0.397

Drills, plywood and lumber at 49/64 in

Drills either side of 49/64 in
DrillSizeOff by
19 mm0.748 in−0.4469 mm
19.5 mm0.7677 in+0.0531 mm

Every drill is on the drill bit size chart.

Bits of this size

Sizes either side

FractionDecimalmm
3/4 in0.75 in19.050 mm
25/32 in0.78125 in19.844 mm

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