ANSI Wood Screw Standards: B18.6.1
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The American National Standards Institute (ANSI) is a private non-profit that oversees the development of standards for products and systems in the United States. They are a HUGE organization with thousands of standards founded in 1918. For our purposes, we're interested in the fastener standards which are very useful.
Imagine if there were no standard sizing for fasteners. The wood screw you bought from Company A might not fit the cup washers you had to get from Company B. But thanks to ANSI, a number 8 wood screw is the same size no matter where it comes from, and the taper on it's head is the same too. ANSI is basically saving us all from a world of aggravation.
There are books and books of ANSI standards and much could be written about their history and usefulness but what you came for was the wood screw standards. Use our handy diagram and table below:
Nominal
Size |
Threads
per Inch |
O
Tot. Hgt. of Head |
K
Height of Head |
T
Depth of Slot |
U
Depth of Slot |
V
Depth of Slot |
|||||
Max.
|
Min.
|
Max.
|
Min.
|
Max.
|
Min.
|
Max.
|
Min.
|
Max..
|
Min
|
||
0
|
32
|
.056
|
.041
|
.039
|
.031
|
.015
|
.010
|
.022
|
.014
|
.030
|
.025
|
1
|
28
|
.068
|
.052
|
.046
|
.038
|
.019
|
.012
|
.027
|
.018
|
.038
|
.031
|
2
|
26
|
.080
|
.063
|
.053
|
.045
|
.023
|
.015
|
.031
|
.022
|
.045
|
.037
|
3
|
24
|
.092
|
.073
|
.060
|
.051
|
.027
|
.017
|
.035
|
.027
|
.052
|
.043
|
4
|
22
|
.104
|
.084
|
.068
|
.058
|
.030
|
.020
|
.040
|
.030
|
.059
|
.049
|
5
|
20
|
.116
|
.095
|
.075
|
.065
|
.034
|
.022
|
.045
|
.034
|
.067
|
.055
|
6
|
18
|
.128
|
.105
|
.082
|
.072
|
.038
|
.024
|
.050
|
.037
|
.074
|
.060
|
7
|
16
|
.140
|
.116
|
.089
|
.079
|
.041
|
.027
|
.054
|
.041
|
.081
|
.066
|
8
|
15
|
.152
|
.126
|
.096
|
.085
|
.045
|
.029
|
.058
|
.045
|
.088
|
.072
|
9
|
14
|
.164
|
.137
|
.103
|
.092
|
.049
|
.032
|
.063
|
.049
|
.095
|
.078
|
10
|
13
|
.176
|
.148
|
.110
|
.099
|
.053
|
.034
|
.068
|
.053
|
.103
|
.084
|
12
|
11
|
.200
|
.169
|
.125
|
.112
|
.060
|
.039
|
.077
|
.061
|
.117
|
.096
|
14
|
10
|
.232
|
.197
|
.144
|
.130
|
.070
|
.046
|
.087
|
.070
|
.136
|
.112
|
16
|
9
|
.248
|
.212
|
.153
|
.139
|
.075
|
.049
|
.093
|
.074
|
.146
|
.120
|
18
|
8
|
.290
|
.249
|
.178
|
.162
|
.083
|
.054
|
.106
|
.085
|
.171
|
.141
|
20
|
8
|
.296
|
.254
|
.182
|
.166
|
.090
|
.059
|
.108
|
.087
|
.175
|
.144
|
24
|
7
|
.347
|
.300
|
.212
|
.195
|
.106
|
.070
|
.124
|
.100
|
.204
|
.168
|