Skip to content
Woodworking Math

5/32 inch in decimal and mm

Decimal inches

0.15625 in

0.1563 in to four places

Millimetres

3.96875 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: 5/32 in = 5 ÷ 32 = 0.15625 in.
  2. An inch is exactly 25.4 mm, so 0.15625 × 25.4 = 3.96875 mm, or 3.969 mm to three places.
  3. In feet, divide by 12: 0.15625 ÷ 12 = 0.013021 ft. In centimetres, divide the mm by 10: 0.396875 cm.
  4. The same size in finer steps: 5/32 = 10/64. A tape marked in 16ths, 32nds or 64ths shows it at those marks.

5/32 to the nearest 1/8, 1/16

A tape or rule marked more coarsely than 32ths can’t show 5/32 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)
1/81/8 in−0.03125−0.794
1/163/16 in+0.03125+0.794

Drills, plywood and lumber at 5/32 in

Drills either side of 5/32 in
DrillSizeOff by
3.9 mm0.1535 in−0.0688 mm
4 mm0.1575 in+0.0313 mm

Every drill is on the drill bit size chart.

Bits of this size

Sizes either side

FractionDecimalmm
9/64 in0.140625 in3.572 mm
11/64 in0.171875 in4.366 mm

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