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Wood Screw Dimensions, Sizes, Head Diameters & Threads per Inch
Nominal
Screw
Size
Threads
per
Inch
Basic Diameter
of Screw
Average Head Diameter
Flat & Oval
Round
Decimal
Fraction
Decimal
Fraction
Decimal
Fraction
0
32
0.060
1/16
0.109
7/64
0.106
7/64
1
28
0.073
5/64
0.135
9/64
0.130
1/8
2
26
0.086
3/32
0.160
5/32
0.154
5/32
3
24
0.099
3/32
0.185
3/16
0.178
11/64
4
22
0.112
7/64
0.210
13/64
0.202
13/64
5
20
0.125
1/8
0.236
15/64
0.227
7/32
6
18
0.138
9/64
0.262
17/64
0.250
1/4
7
16
0.151
5/32
0.287
9/32
0.275
9/32
8
15
0.164
5/32
0.312
5/16
0.298
19/64
9
14
0.177
11/64
0.337
11/32
0.323
21/64
10
13
0.190
3/16
0.363
23/64
0.347
11/32
12
11
0.216
7/32
0.414
13/32
0.395
25/64
14
10
0.242
15/64
0.480
31/64
0.443
7/16
16
9
0.268
17/64
0.515
33/64
0.491
31/64
18
8
0.294
19/64
0.602
19/32
0.539
17/32
20
8
0.320
5/16
0.616
39/64
0.587
19/32
24
7
0.372
3/8
0.724
23/32
0.683
11/16
NOTES:
1. Unless noted otherwise, all dimensions are in inches.
2. Fractional size is decimal size rounded to nearest 64th.
3. For reference only.