Unified External Screw Threads

Data for industrial machine screws, threaded fasteners and standard industrial fasteners from Elgin Fastener Group includes unified external screw threads. Diameters and sizes for class 2A and 3A UNRC. and UNRF. and ISO metric threads are listed in the chart below.

Classes 2A & 3A UNRC. UNRF.

Nominal Size & TPI Class 2A Class 3A
Major Diameter Pitch
Diameter
Major Diameter Pitch Diameter Blank
Size
4-40 .1061
.1112
.0925
.0950
.1069
.1120
.0939
.0958
.0938
.0943
4-48 .1068
.1113
.0954
.0978
.1075
.1120
.0967
.0985
.0968
.0971
5-40 .1191
.1242
.1054
.1080
.1199
.1250
.1060
.1088
.1067
.1072
5-44 .1195
.1243
.1070
.1095
.1202
.1250
.1083
.1102
.1083
.1088
6-32 .1312
.1372
.1141
.1169
.1320
.1380
.1156
.1177
.1155
.1161
6-40 .1321
.1372
.1184
.1210
.1329
.1380
.1198
.1218
.1197
.1202
8-32 .1571
.1631
.1399
.1428
.1580
.1640
.1415
.1437
.1414
.1419
8-36 .1577
.1632
.1424
.1452
.1585
.1640
.1439
.1460
.1438
.1444
10-24 .1818
.1890
.1586
.1619
.1828
.1900
.1604
.1629
.1603
.1609
10-32 .1831
.1891
.1658
.1688
.1840
.1900
.1674
.1697
.1673
.1679
12-24 .2078
.2150
.1845
.1879
.2088
.2160
.1863
.1889
.1862
.1867
12-28 .2085
.2150
.1888
.1918
.2095
.2160
.1904
.1928
.1903
.1908
1/4-20 .2408
.2489
.2127
.2164
.2419
.2500
.2147
.2175
.2146
.2153
1/4-28 .2425
.2490
.2225
.2258
.2435
.2500
.2243
.2268
.2242
.2248
5/16-18 .3026
.3113
.2712
.2752
.3038
.3125
.2734
.2764
.2732
.2740
5/16-24 .3042
.3114
.2806
.2843
.3053
.3125
.2827
.2854
.2825
.2832
3/8-16 .3643
.3737
.3287
.3331
.3656
.3750
.3311
.3344
.3309
.3318
3/8-24 .3667
.3739
.3430
.3468
.3678
.3750
.3450
.3479
.3449
.3457
7/16-14 .4258
.4361
.3850
.3897
.4272
.4375
.3876
.3911
.3874
.3883
7/16-20 .4281
.4362
.3995
.4037
.4294
.4375
.4019
.4050
.4016
.4024
1/2-13 .4876
.4985
.4435.4485 .4891
.5000
.4463
.4500
.4480
.4470
1/2-20 .4906
.4987
.4619
.4662
.4919
.5000
.4643
.4675
.4641
.4649
9/16-12 .5016
.5068
.5495
.5609
.5045
.5084
.5511
.5625
.5050
.5070
9/16-18 .5205
.5250
.5524
.5611
.523
.5264
.5538
.5625
.5170
.5190
5/8-11 .5589
.5644
.6113
.6234
.5619
.5660
.6129
.6250
.5630
.5650
5/8-18 .5828
.5875
.6149
.6236
.5854
.5889
.6163
.6250
.5840
.5860

 

ISO Metric Threads — CLASS 6g

Metric Size Inch Measurement Millimeters
Nominal Size Major Diameter Pitch Diameter Blank Size Major Diameter Pitch Diameter Blank
Size
M3 x .5 .1173
.1131
.1045
.1016
.1037
.1030
2.980
2.874
2.655
2.580
2.635
2.615
M3.5 x .6 .1370
.1320
.1216
.1183
.1205
.1195
3.479
3.354
3.089
3.004
3.060
3.035
M4 x .7 .1566
.1511
.1387
.1352
.1376
.1364
3.978
3.938
3.523
3.438
3.495
3.465
M5 x .8 .1959
.1900
.1754
.1717
.1742
.1730
4.976
4.826
4.456
4.361
4.425
4.395
M6 x 1.0 .2352
.2281
.2096
.2052
.2087
.2071
5.974
5.794
5.324
5.212
5.300
5.260
M7 x 1.0 .2746
.2675
.2490
.2446
.2480
.2465
6.974
6.794
6.324
6.212
6.300
6.260
M8 x 1.25 .3139
.3055
.2819
.2772
.2807
.2791
7.972
7.760
7.160
7.042
7.130
7.090
M10 x 1.25 .3926
.3856
.3606
.3560
.3594
.3579
9.972
9.794
9.160
9.042
9.130
9.090
M10 x 1.5 .3924
.3831
.3541
.3489
.3528
.3512
9.968
9.732
8.994
8.862
8.960
8.920
M11 x 1.5 .4318
.4225
.3935
.3883
.3921
.3902
10.968
10.732
9.994
9.862
9.960
9.910
M12 x 1.25 .4713
.4630
.4394
.4342
.4382
.4366
11.972
11.760
11.160
11.028
11.130
11.090
M12 x 1.75 .4711
.4607
.4263
.4204
.4252
.4232
11.966
11.701
10.829
10.679
10.800
10.750

 

ISO Metric Threads — CLASS 4h

Metric Size Inch Measurement Millimeters
Nominal Size Major Diameter Pitch Diameter Blank Size Major Diameter Pitch Diameter Blank
Size
M3 x .5 .1181
.1155
.1053
.1034
.1051
.1046
3.000
2.933
2.675
2.627
2.669
2.656
M3 .5 x .6 .1378
.1321
.1216
.1183
.1212
.1205
3.500
3.355
3.088
3.004
3.078
3.060
M4 x .7 .1575
.1539
.1396
.1374
.1394
.1387
4.000
3.910
3.545
3.489
3.540
3.522
M5 x .8 .1968
.1931
.1751
.1740
.1748
.1741
5.000
4.905
4.480
4.420
4.439
4.422
M6 x 1.0 .2362
.2318
.2106
.2078
.2100
.2093
6.000
5.888
5.350
5.279
5.334
5.316
M7 x 1.0 .2756
.2712
.2500
.2472
.2494
.2487
7.000
6.888
6.350
6.279
6.334
6.316
M8 x 1.25 .3150
.3098
.2830
.2800
.2826
.2819
8.000
7.868
7.188
7.113
7.178
7.160
M10 x 1.0 .3937
.3893
.3681
.3653
.3675
.3668
10.000
9.888
9.350
9.279
9.334
8.554
M10 x 1.25 .3937
.3885
.3617
.3588
.3610
.3603
10.000
9.868
9.188
9.113
9.169
9.151
M10 x 1.5 .3937
.3878
.3553
.3520
.3551
.3544
10.000
9.850
9.026
8.941
9.020
9.001
M12 x 1.25 .4724
.4672
.4405
.4371
.4397
.4390
12.000
11.868
11.188
11.103
11.168
11.150
M12 x 1.5 .4724
.4665
.4341
.4305

.4335
.4328

12.000
11.850
11.026
10.936
11.010
10.993
M12 x 1.75 .4724
.4657
.4277
.4239
.4273
.4265
12.000
11.830
10.863
10.768
10.853
10.833