21/32 inch in decimal and mm
Decimal inches
0.65625 in
0.6563 in to four places
Millimetres
16.66875 mm
From the standard, the international inch, 25.4 mm exactly
The math
- A fraction is its top number divided by its bottom number: 21/32 in = 21 ÷ 32 = 0.65625 in.
- An inch is exactly 25.4 mm, so 0.65625 × 25.4 = 16.66875 mm, or 16.669 mm to three places.
- In feet, divide by 12: 0.65625 ÷ 12 = 0.054688 ft. In centimetres, divide the mm by 10: 1.666875 cm.
- The same size in finer steps: 21/32 = 42/64. A tape marked in 16ths, 32nds or 64ths shows it at those marks.
21/32 to the nearest 1/8, 1/16
A tape or rule marked more coarsely than 32ths can’t show 21/32 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):
| Nearest | Mark | Off by (in) | Off by (mm) |
|---|---|---|---|
| 1/8 | 5/8 in | −0.03125 | −0.794 |
| 1/16 | 11/16 in | +0.03125 | +0.794 |
Drills, plywood and lumber at 21/32 in
| Drill | Size | Off by |
|---|---|---|
| 16.5 mm | 0.6496 in | −0.1687 mm |
| 17 mm | 0.6693 in | +0.3313 mm |
Every drill is on the drill bit size chart.
Bits of this size
Sizes either side
Every size is on the fraction to decimal chart; any other size goes in the fraction to decimal calculator.