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Nominal Thread SizeCovered Range
0-80 UNF to ¼-56 UNS Nominal thread sizes from 0-80 UNF to ¼-56 UNS
5/16-18 UNC to 9/16 -32 UN Nominal thread sizes from 5/16-18 UNC to 9/16 -32 UN
5/8-11 UNC to 7/8-32 UN Nominal thread sizes from 5/8-11 UNC to 7/8-32 UN
15/16-12 UN to 1 3/16-28 UN Nominal thread sizes from 15/16-12 UN to 1 3/16-28 UN
1 1/4-7 UNC to 1 9/16-20 UN Nominal thread sizes from 1 1/4-7 UNC to 1 9/16-20 UN
1 5/8-6 UN to 1 15/16-20 UN Nominal thread sizes from 1 5/8-6 UN to 1 15/16-20 UN
2-4½ UNC to 2¾-20 UN Nominal thread sizes from 2-4½ UNC to 2¾-20 UN
2 7/8-6 UN to 4-16 UN Nominal thread sizes from 2 7/8-6 UN to 4-16 UN
 
External Thread /Internal Thread
  Nominal Size, TPI, Series Class Allowance Maxa Major
Max Minor
Min Major
Min Minor
Min b Maxa Pitch Min Pitch UNRc Minor Dia
Major Dia(Min)
Ext. 15/16-12 UN 2A 0.0017 0.9358 0.9244 - 0.8817 0.8760 0.8366
Int.   2B   0.8650 0.8470   0.8908 0.8834 0.9375
Ext. 15/16-12 UN 3A 0.0000 0.9375 0.9261 - 0.8834 0.8793 0.8383
Int.   3B   0.8575 0.8470   0.8889 0.8834 0.9375
Ext. 15/16-16 UN 2A 0.0015 0.9360 0.9266 - 0.8954 0.8904 0.8615
Int.   2B   0.8840 0.8700   0.9034 0.8969 0.9375
Ext. 15/16-16 UN 3A 0.0000 0.9375 0.9281 - 0.8969 0.8932 0.8630
Int.   3B   0.8783 0.8700   0.9018 0.8969 0.9375
Ext. 15/16-20 UNEF 2A 0.0014 0.9361 0.9280 - 0.9036 0.8991 0.8766
Int.   2B   0.8950 0.8830   0.9109 0.9050 0.9375
Ext. 15/16-20 UNEF 3A 0.0000 0.9375 0.9294 - 0.9050 0.9016 0.8780
Int.   3B   0.8912 0.8830   0.9094 0.9050 0.9375
Ext. 15/16-28 UN 2A 0.0012 0.9363 0.9298 - 0.9131 0.9091 0.8937
Int.   2B   0.9070 0.8990   0.9195 0.9143 0.9375
Ext. 15/16-28 UN 3A 0.0000 0.9375 0.9310 - 0.9143 0.9113 0.8949
Int.   3B   0.9051 0.8990   0.9182 0.9143 0.9375
Ext. 15/16-32 UN 2A 0.0011 0.9364 0.9304 - 0.9161 0.9123 0.8992
Int.   2B   0.9110 0.9040   0.9221 0.9172 0.9375
Ext. 15/16-32 UN 3A 0.0000 0.9375 0.9315 - 0.9172 0.9144 0.9003
Int.   3B   0.9094 0.9040   0.9209 0.9172 0.9375
Ext. 1-8 UNC 1A 0.0020 0.9980 0.9755 - 0.9168 0.9067 0.8492
Int.   1B   0.8900 0.8650   0.9320 0.9188 1.0000
Ext. 1-8 UNC 2A 0.0020 0.9980 0.9830 0.9755 0.9168 0.9100 0.8492
Int.   2B   0.8900 0.8650   0.9276 0.9188 1.0000
Ext. 1-8 UNC 3A 0.0000 1.0000 0.9850 - 0.9188 0.9137 0.8512
Int.   3B   0.8797 0.8650   0.9254 0.9188 1.0000
Ext. 1-10 UNS 2A 0.0018 0.9982 0.9853 - 0.9332 0.9270 0.8792
Int.   2B   0.9130 0.8920   0.9430 0.9350 1.0000
Ext. 1-12 UNF 1A 0.0018 0.9982 0.9810 - 0.9441 0.9353 0.8990
Int.   1B   0.9280 0.9100   0.9573 0.9459 1.0000
Ext. 1-12 UNF 2A 0.0018 0.9982 0.9868 - 0.9441 0.9382 0.8990
Int.   2B   0.9280 0.9100   0.9535 0.9459 1.0000
Ext. 1-12 UNF 3A 0.0000 1.0000 0.9886 - 0.9459 0.9415 0.9008
Int.   3B   0.9198 0.9100   0.9516 0.9459 1.0000
Ext. 1-14UNS 1A 0.0017 0.9983 0.9828 - 0.9519 0.9435 0.9132
Int.   1B   0.9380 0.9230   0.9645 0.9536 1.0000
Ext. 1-14UNS 2A 0.0017 0.9983 0.9880 - 0.9519 0.9463 0.9132
Int.   2B   0.9380 0.9230   0.9609 0.9536 1.0000
Ext. 1-14UNS 3A 0.0000 1.0000 0.9897 - 0.9536 0.9494 0.9149
Int.   3B   0.9315 0.9230   0.9590 0.9536 1.0000
Ext. 1-16 UN 2A 0.0015 0.9985 0.9891 - 0.9579 0.9529 0.9240
Int.   2B   0.9460 0.9320   0.9659 0.9594 1.0000
Ext. 1-16 UN 3A 0.0000 1.0000 0.9906 - 0.9594 0.9557 0.9255
Int.   3B   0.9408 0.9320   0.9643 0.9594 1.0000
Ext. 1-18 UNS 2A 0.0014 0.9986 0.9899 - 0.9625 0.9578 0.9325
Int.   2B   0.9530 0.9400   0.9701 0.9639 1.0000
Ext. 1-20 UNEF 2A 0.0014 0.9986 0.9905 - 0.9661 0.9616 0.9391
Int.   2B   0.9570 0.9460   0.9734 0.9675 1.0000
Ext. 1-20 UNEF 3A 0.0000 1.0000 0.9919 - 0.9675 0.9641 0.9405
Int.   3B   0.9537 0.9460   0.9719 0.9675 1.0000
Ext. 1-24 UNS 2A 0.0013 0.9987 0.9915 - 0.9716 0.9674 0.9491
Int.   2B   0.9650 0.9550   0.9784 0.9729 1.0000
Ext. 1-27 UNS 2A 0.0012 0.9988 0.9921 - 0.9747 0.9707 0.9547
Int.   2B   0.9690 0.9600   0.9811 0.9759 1.0000
Ext. 1-28 UN 2A 0.0012 0.9988 0.9923 - 0.9756 0.9716 0.9562
Int.   2B   0.9700 0.9610   0.9820 0.9768 1.0000
Ext. 1-28 UN 3A 0.0000 1.0000 0.9935 - 0.9768 0.9738 0.9574
Int.   3B   0.9676 0.9610   0.9807 0.9768 1.0000
Ext. 1-32 UN 2A 0.0011 0.9989 0.9929 - 0.9786 0.9748 0.9617
Int.   2B   0.9740 0.9660   0.9846 0.9797 1.0000
Ext. 1-32 UN 3A 0.0000 1.0000 0.9940 - 0.9797 0.9769 0.9628
Int.   3B   0.9719 0.9660   0.9834 0.9797 1.0000
Ext. 11/16-8 UN 2A 0.0020 1.0605 1.0455 - 0.9793 0.9725 0.9117
Int.   2B   0.9520 0.9270   0.9902 0.9813 1.0625
Ext. 11/16-8 UN 3A 0.0000 1.0625 1.0475 - 0.9813 0.9762 0.9137
Int.   3B   0.9422 0.9270   0.9880 0.9813 1.0625
Ext. 11/16-12 UN 2A 0.0017 1.0608 1.0494 - 1.0067 1.0010 0.9616
Int.   2B   0.9900 0.9720   1.0158 1.0084 1.0625
Ext. 11/16-12 UN 3A 0.0000 1.0625 1.0511 - 1.0084 1.0042 0.9633
Int.   3B   0.9823 0.9720   1.0139 1.0084 1.0625
Ext. 11/16-16 UN 2A 0.0015 1.0610 1.0516 - 1.0204 1.0154 0.9865
Int.   2B   1.0090 0.9950   1.0284 1.0219 1.0625
Ext. 11/16-16 UN 3A 0.0000 1.0625 1.0531 - 1.0219 1.0182 0.9880
Int.   3B   1.0033 0.9950   1.0268 1.0219 1.0625
Ext. 11/16-18 UNEF 2A 0.0014 1.0611 1.0524 - 1.0250 1.0203 0.9950
Int.   2B   1.0150 1.0020   1.0326 1.0264 1.0625
Ext. 11/16-18 UNEF 3A 0.0000 1.0625 1.0538 - 1.0264 1.0228 0.9964
Int.   3B   1.0105 1.0020   1.0310 1.0264 1.0625
Ext. 11/16-20 UN 2A 0.0014 1.0611 1.0530 - 1.0286 1.0241 1.0016
Int.   2B   1.0200 1.0080   1.0359 1.0300 1.0625
Ext. 11/16-20 UN 3A 0.0000 1.0625 1.0544 - 1.0300 1.0266 1.0030
Int.   3B   1.0162 1.0080   1.0344 1.0300 1.0625
Ext. 11/16-28 UN 2A 0.0012 1.0613 1.0548 - 1.0381 1.0341 1.0187
Int.   2B   1.0320 1.0240   1.0445 1.0393 1.0625
Ext. 11/16-28 UN 3A 0.0000 1.0625 1.0560 - 1.0393 1.0363 1.0199
Int.   3B   1.0301 1.0240   1.0432 1.0393 1.0625
Ext. 11/8-7 UNC 1A 0.0022 1.1228 1.0982 - 1.0300 1.0191 0.9527
Int.   1B   0.9980 0.9700   1.0463 1.0322 1.1250
Ext. 11/8-7 UNC 2A 0.0022 1.1228 1.1064 1.0982 1.0300 1.0228 0.9527
Int.   2B   0.9980 0.9700   1.0416 1.0322 1.1250
Ext. 11/8-7 UNC 3A 0.0000 1.1250 1.1086 - 1.0322 1.0268 0.9549
Int.   3B   0.9875 0.9700   1.0393 1.0322 1.1250
Ext. 11/8-8 UN 2A 0.0021 1.1229 1.1079 1.1004 1.0417 1.0348 0.9741
Int.   2B   1.0150 0.9900   1.0528 1.0438 1.1250
Ext. 11/8-8 UN 3A 0.0000 1.1250 1.1100 - 1.0438 1.0386 0.9762
Int.   3B   1.0047 0.9900   1.0505 1.0438 1.1250
Ext. 11/8-10 UNS 2A 0.0018 1.1232 1.1103 - 1.0582 1.0520 1.0042
Int.   2B   1.0380 1.0170   1.0680 1.0600 1.1250
Ext. 11/8-12 UNF 1A 0.0018 1.1232 1.1060 - 1.0691 1.0601 1.0240
Int.   1B   1.0530 1.0350   1.0826 1.0709 1.1250
Ext. 11/8-12 UNF 2A 0.0018 1.1232 1.1118 - 1.0691 1.0631 1.0240
Int.   2B   1.0530 1.0350   1.0787 1.0709 1.1250
Ext. 11/8-12 UNF 3A 0.0000 1.1250 1.1136 - 1.0709 1.0664 1.0258
Int.   3B   1.0448 1.0350   1.0768 1.0709 1.1250
Ext. 11/8-14 UNS 2A 0.0016 1.1234 1.1131 - 1.0770 1.0717 1.0384
Int.   2B   1.0640 1.0480   1.0855 1.0786 1.1250
Ext. 11/8-16 UN 2A 0.0015 1.1235 1.1141 - 1.0829 1.0779 1.0490
Int.   2B   1.0710 1.0570   1.0909 1.0844 1.1250
Ext. 11/8-16 UN 3A 0.0000 1.1250 1.1156 - 1.0844 1.0807 1.0505
Int.   2B   1.0658 1.0570   1.0893 1.0844 1.1250
Ext. 11/8-18 UNEF 2A 0.0014 1.1236 1.1149 - 1.0875 1.0828 1.0575
Int.   2B   1.0780 1.0650   1.0951 1.0889 1.1250
Ext. 11/8-18 UNEF 3A 0.0000 1.1250 1.1163 - 1.0889 1.0853 1.0589
Int.   3B   1.0730 1.0650   1.0935 1.0889 1.1250
Ext. 11/8-20 UN 2A 0.0014 1.1236 1.1155 - 1.0911 1.0866 1.0641
Int.   2B   1.0820 1.0710   1.0984 1.0925 1.1250
Ext. 11/8-20 UN 3A 0.0000 1.1250 1.1169 - 1.0925 1.0891 1.0655
Int.   3B   1.0787 1.0710   1.0969 1.0925 1.1250
Ext. 11/8-24 UNS 2A 0.0013 1.1237 1.1165 - 1.0966 1.0924 1.0742
Int.   2B   1.0900 1.0800   1.1034 1.0979 1.1250
Ext. 11/8-28 UN 2A 0.0012 1.1238 1.1173 - 1.1006 1.0966 1.0812
Int.   2B   1.0950 1.0860   1.1070 1.1018 1.1250
Ext. 11/8-28 UN 3A 0.0000 1.1250 1.1185 - 1.1018 1.0988 1.0824
Int.   3B   1.0926 1.0860   1.1057 1.1018 1.1250
Ext. 13/16-8 UN 2A 0.0021 1.1854 1.1704 - 1.1042 1.0972 1.0366
Int.   2B   1.0770 1.0520   1.1154 1.1063 1.1875
Ext. 13/16-8 UN 3A 0.0000 1.1875 1.1725 - 1.1063 1.1011 1.0387
Int.   3B   1.0672 1.0520   1.1131 1.1063 1.1875
Ext. 13/16-12 UN 2A 1.0017 1.1858 1.1744 - 1.1317 1.1259 1.0866
Int.   2B   1.1150 1.0970   1.1409 1.1334 1.1875
Ext. 13/16-12 UN 3A 0.0000 1.1872 1.1761 - 1.1334 1.1291 1.0883
Int.   3B   1.1073 1.0970   1.1390 1.1334 1.1875
Ext. 13/16-16 UN 2A 0.0015 1.1860 1.1766 - 1.1454 1.1403 1.1115
Int.   2B   1.1340 1.1200   1.1535 1.1469 1.1875
Ext. 13/16-16 UN 3A 0.0000 1.1875 1.1781 - 1.1469 1.1431 1.1130
Int.   3B   1.1283 1.1200   1.1519 1.1469 1.1875
Ext. 13/16-18 UNEF 2A 0.0015 1.1860 1.1773 - 1.1499 1.1450 1.1199
Int.   2B   1.1400 1.1270   1.1577 1.1514 1.1875
Ext. 13/16-18 UNEF 3A 0.0000 1.1875 1.1788 - 1.1514 1.1478 1.1214
Int.   3B   1.1355 1.1270   1.1561 1.1514 1.1875
Ext. 13/16-20 UN 2A 0.0014 1.1861 1.1780 - 1.1536 1.1489 1.1266
Int.   2B   1.1450 1.1330   1.1611 1.1550 1.1875
Ext. 13/16-20 UN 3A 0.0000 1.1875 1.1794 - 1.1550 1.1515 1.1280
Int.   3B   1.1412 1.1330   1.1595 1.1550 1.1875
Ext. 13/16-28 UN 2A 0.0012 1.1863 1.1798 - 1.1631 1.1590 1.1437
Int.   2B   1.1570 1.1490   1.1696 1.1643 1.1875
Ext. 13/16-28 UN 3A 0.0000 1.1875 1.1810 - 1.1643 1.1612 1.1449
Int.   3B   1.1551 1.1490   1.1683 1.1643 1.1875
a For Class 2A threads with coating (plating) the max. is increased by the allowance, to the basic size. This is the same value as Class 3A.
b For uncoated hot-rolled, but not standard fasteners with cold rolled threads
c UN series external thread, Max.Diameter = Basic - Allowance, for Class 1A and 2A
  = Basic for Class 3A
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Glossary
Selecting the Right 3D Printer

Discover how to choose the right 3D printer for your needs and the key performance attributes to consider.

Injection Molding Design Guide

Guide for high quality and cost-effective plastic injection molding.

CNC Machining Design Guide

Optimize your designs, reduce machining time, and lower your costs.

Metal 3D Printing Design Guide

Direct Metal Laser Sintering (DMLS) 3D printing for parts with reduced cost and little waste.