US Wood Screw Dimensions, Sizes, Head Diameters & Threads per Inch
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. Major thread diameter is measured on the outside of the threads. 4. For reference only.