Thread Pitch Chart
A
A
As
As
s
r
s
n
Thread Stripping Areas sq. in. per in. of Engagement
Nominal Size, Threads
Tensile
Thread Root
per inch and Thread Series
Stress Area
External Thread
Internal Thread
Area sq. in.
sq. in.
Class 2A
Class 3A
Class 2B
Class 3B
0 ‐ 80
UNF
0.00180
0.00151
0.0673
0.0748
0.106
0.116
1 ‐ 64
UNC
0.00263
0.00218
0.0835
0.0913
0.133
0.144
1 ‐ 72
UNF
0.00278
0.00237
0.0831
0.0922
0.130
0.142
2 ‐ 56
UNC
0.00370
0.00310
0.101
0.109
0.162
0.174
2 ‐ 64
UNF
0.00394
0.00339
0.101
0.110
0.156
0.170
3 ‐ 48
UNC
0.00487
0.00406
0.118
0.127
0.191
0.204
3 ‐ 56
UNF
0.00523
0.00451
0.118
0.130
0.186
0.201
4 ‐ 40
UNC
0.00604
0.00496
0.138
0.147
0.221
0.235
4 ‐ 48
UNF
0.00661
0.00566
0.140
0.151
0.216
0.232
5 ‐ 40
UNC
0.00796
0.00672
0.161
0.172
0.248
0.263
5 ‐ 44
UNF
0.00830
0.00716
0.162
0.173
0.246
0.262
6 ‐ 32
UNC
0.00909
0.00745
0.180
0.189
0.281
0.296
6 ‐ 40
UNF
0.01015
0.00874
0.182
0.197
0.0274
0.292
8 ‐ 32
UNC
0.0140
0.0120
0.226
0.239
0.334
0.353
8 ‐ 36
UNF
0.0147
0.0128
0.227
0.244
0.331
0.350
10 ‐ 24
UNC
0.0175
0.0145
0.263
0.227
0.401
0.420
10 ‐ 32
UNF
0.0200
0.0175
0.275
0.289
0.389
0.411
12 ‐ 24
UNC
0.0242
0.0206
0.312
0.327
0.458
0.478
12 ‐ 28
UNF
0.0258
0.0226
0.317
0.336
0.450
0.474
1/4 ‐ 20
UNC
0.0318
0.0269
0.368
0.385
0.539
0.563
1/4 ‐ 28
UNF
0.0364
0.0326
0.373
0.403
0.521
0.549
5/16 ‐ 18
UNC
0.0524
0.0454
0.470
0.502
0.682
0.710
5/16 ‐ 24
UNF
0.0580
0.0524
0.479
0.520
0.663
0.696
3/8 ‐ 16
UNC
0.0775
0.0678
0.576
0.619
0.828
0.860
3/8 ‐ 24
UNF
0.0878
0.0809
0.578
0.644
0.800
0.387
7/16 ‐ 14
UNC
0.106
0.0933
0.677
0.734
0.981
1.01
7/16 ‐ 20
UNF
0.119
0.109
0.685
0.761
0.908
0.991
1/2 ‐ 13
UNC
0.142
0.126
0.779
0.854
1.12
1.16
1/2 ‐ 20
UNF
0.160
0.149
0.799
0.887
1.08
1.13
9/16 ‐ 12
UNC
0.182
0.162
0.893
0.974
1.27
1.32
9/16 ‐ 18
UNF
0.203
0.189
0.901
1.02
1.23
1.29
5/8 ‐ 11
UNC
0.226
0.202
0.998
1.09
1.42
1.47
5/8 ‐ 18
UNF
0.256
0.240
0.998
1.13
1.37
1.43
3/4 ‐ 10
UNC
0.334
0.302
1.21
1.34
1.72
1.78
3/4 ‐ 16
UNF
0.373
0.351
1.23
1.38
1.66
1.73
7/8 ‐ 9
UNC
0.462
0.419
1.43
1.58
2.03
2.09
7/8 ‐ 14
UNF
0.0509
0.480
1.44
1.63
1.96
2.03
1 ‐ 8
UNC
0.606
0.551
1.66
1.82
2.33
2.40
1 ‐ 12
UNF
0.663
0.625
1.66
1.87
2.27
2.35
1 ‐ 14
UNS
0.680
0.646
1.67
1.89
2.23
2.33
1-1/8 ‐ 6
UNC
0.763
0.693
1.88
2.04
2.65
2.72
1-1/8 ‐ 8
UN
0.790
0.728
1.89
2.07
2.63
2.70
1-1/4 ‐ 7
UNC
0.969
0.890
2.11
2.30
2.94
3.02
1-1/4 ‐ 8
UN
1.000
0.929
2.12
2.33
2.92
3.00
1-3/8 ‐ 6
UNC
1.16
1.05
2.34
2.52
3.27
3.35
1-3/8 ‐ 8
UN
1.23
1.16
2.34
2.58
3.21
3.30
1-1/2 ‐ 6
UNC
1.41
1.29
2.58
2.77
3.57
3.65
1-1/2 ‐ 8
UN
1.49
1.41
2.57
2.84
3.50
3.61
1-5/8 ‐ 8
UN
1.78
1.68
2.80
3.10
3.79
3.91
1-3/4 ‐ 5
UNC
1.90
1.74
3.04
3.24
4.20
4.30
1-3/4 ‐ 8
UN
2.08
1.98
3.03
3.35
4.08
4.21
1-7/8 ‐ 8
UN
2.41
2.30
3.25
3.63
4.37
4.50
This technical information is supplied as a courtesy. All-Pro Fasteners, Inc. neither employs nor maintains an engineering or technical staff,
and All-Pro is merely supplying certain manufacturing, technical, and/or design specifications and data received by All-Pro Fasteners, Inc. from
the products’ manufacturer or taken from consensus standards, and is in no manner originated, developed, created, enhanced, altered, or approved
by All-Pro Fasteners, Inc.