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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. 15/8-6 UN 2A 0.0025 1.6225 1.6043 - 1.5142 1.5060 1.4246
Int.   2B   1.4750 1.4450   1.5274 1.5167 1.6250
Ext. 15/8-6 UN 3A 0.0000 1.6250 1.6068 - 1.5167 1.5105 1.4271
Int.   3B   1.4646 1.4450   1.5247 1.5167 1.6250
Ext. 15/8-8 UN 2A 0.0022 1.6228 1.6078 1.6003 1.5416 1.5342 1.4784
Int.   2B   1.5150 1.4900   1.5535 1.5438 1.6250
Ext. 15/8-8 UN 3A 0.0000 1.6250 1.6100 - 1.5438 1.5382 1.4806
Int.   3B   1.5047 1.4900   1.5510 1.5438 1.6250
Ext. 15/8-10 UNS 2A 0.0019 1.6231 1.6102 - 1.5581 1.5517 1.5041
Int.   2B   1.5380 1.5170   1.5683 1.5600 1.6250
Ext. 15/8-12 UN 2A 0.0018 1.6232 1.6118 - 1.5691 1.5632 1.5240
Int.   2B   1.5530 1.5350   1.5785 1.5709 1.6250
Ext. 15/8-12 UN 3A 0.0000 1.6250 1.6136 - 1.5709 1.5665 1.5258
Int.   3B   1.5448 1.5350   1.5766 1.5709 1.6250
Ext. 15/8-14 UNS 2A 0.0017 1.6233 1.6130 - 1.5769 1.5714 1.5383
Int.   2B   1.5640 1.5480   1.5858 1.5786 1.6250
Ext. 15/8-16 UN 2A 0.0016 1.6234 1.6140 - 1.5828 1.5776 1.5489
Int.   2B   1.5710 1.5570   1.5912 1.5844 1.6250
Ext. 15/8-16 UN 3A 0.0000 1.6250 1.6156 - 1.5844 1.5805 1.5505
Int.   3B   1.5658 1.5570   1.5895 1.5844 1.6250
Ext. 15/8-18 UNEF 2A 0.0015 1.6235 1.6148 - 1.5874 1.5824 1.5574
Int.   2B   1.5780 1.5650   1.5954 1.5889 1.6250
Ext. 15/8-18 UNEF 3A 0.0000 1.6250 1.6163 - 1.5889 1.5852 1.5589
Int.   3B   1.5730 1.5650   1.5937 1.5889 1.6250
Ext. 15/8-20 UN 2A 0.0014 1.6236 1.6155 - 1.5911 1.5863 1.5641
Int.   2B   1.5820 1.5710   1.5987 1.5925 1.6250
Ext. 15/8-20 UN 3A 0.0000 1.6250 1.6169 - 1.5925 1.5889 1.5655
Int.   3B   1.5787 1.5710   1.5971 1.5925 1.6250
Ext. 15/8-24 UNS 2A 0.0013 1.6237 1.6165 - 1.5966 1.5922 1.5741
Int.   2B   1.5900 1.5800   1.6037 1.5979 1.6250
Ext. 111/16-6 UN 2A 0.0025 1.6850 1.6668 - 1.5767 1.5684 1.4866
Int.   2B   1.5380 1.5070   1.5900 1.5792 1.6875
Ext. 111/16-6 UN 3A 0.0000 1.6875 1.6693 - 1.5792 1.5730 1.4891
Int.   3B   1.5271 1.5070   1.5873 1.5792 1.6875
Ext. 111/16-8 UN 2A 0.0022 1.6853 1.6703 - 1.6041 1.5966 1.5365
Int.   2B   1.5770 1.5520   1.6160 1.6063 1.6875
Ext. 111/16-8 UN 3A 0.0000 1.6875 1.6725 - 1.6063 1.6007 1.5387
Int.   3B   1.5672 1.5520   1.6136 1.6063 1.6875
Ext. 111/16-12 UN 2A 0.0018 1.6857 1.6743 - 1.6316 1.6256 1.5865
Int.   2B   1.6150 1.5970   1.6412 1.6334 1.6875
Ext. 111/16-12 UN 3A 0.0000 1.6875 1.6761 - 1.6334 1.6289 1.5883
Int.   3B   1.6073 1.5970   1.6392 1.6334 1.6875
Ext. 111/16-16 UN 2A 0.0016 1.6859 1.6765 - 1.6453 1.6400 1.6114
Int.   2B   1.6340 1.6200   1.6538 1.6469 1.6875
Ext. 111/16-16 UN 3A 0.0000 1.6875 1.6781 - 1.6469 1.6429 1.6130
Int.   3B   1.6283 1.6200   1.6521 1.6469 1.6875
Ext. 111/16-18 UNEF 2A 0.0015 1.6860 1.6773 - 1.6499 1.6448 1.6199
Int.   2B   1.6400 1.6270   1.6580 1.6514 1.6875
Ext. 111/16-18 UNEF 3A 0.0000 1.6875 1.6788 - 1.6514 1.6476 1.6214
Int.   3B   1.6355 1.6270   1.6563 1.6514 1.6875
Ext. 111/16-20 UN 2A 0.0015 1.6860 1.6779 - 1.6535 1.6487 1.6265
Int.   2B   1.6450 1.6330   1.6613 1.6550 1.6875
Ext. 111/16-20 UN 3A 0.0000 1.6875 1.6794 - 1.6550 1.6514 1.6280
Int.   3B   1.6412 1.6330   1.6597 1.6550 1.6875
Ext. 13/4-5 UNC 1A 0.0027 1.7473 1.7165 - 1.6174 1.6040 1.5092
Int.   1B   1.5680 1.5340   1.6375 1.6201 1.7500
Ext. 13/4-5 UNC 2A 0.0027 1.7473 1.7268 1.7165 1.6174 1.6085 1.5092
Int.   2B   1.5680 1.5340   1.6317 1.6201 1.7500
Ext. 13/4-5 UNC 3A 0.0000 1.7500 1.7295 - 1.6201 1.6134 1.5119
Int.   3B   1.5575 1.5340   1.6288 1.6201 1.7500
Ext. 13/4-6 UN 2A 0.0025 1.7475 1.7293 - 1.6392 1.6309 1.5491
Int.   2B   1.6000 1.5700   1.6525 1.6417 1.7500
Ext. 13/4-6 UN 3A 0.0000 1.7500 1.7318 - 1.6417 1.6354 1.5516
Int.   3B   1.5896 1.5700   1.6498 1.6417 1.7500
Ext. 13/4-8 UN 2A 0.0023 1.7477 1.7327 1.7252 1.6665 1.6590 1.5989
Int.   2B   1.6400 1.6150   1.6786 1.6688 1.7500
Ext. 13/4-8 UN 3A 0.0000 1.7500 1.7350 - 1.6688 1.6632 1.6012
Int.   3B   1.6297 1.6150   1.6762 1.6688 1.7500
Ext. 13/4-10 UNS 2A 0.0019 1.7481 1.7352 - 1.6831 1.6766 1.6291
Int.   2B   1.6630 1.6420   1.6934 1.6850 1.7500
Ext. 13/4-12 UN 2A 0.0018 1.7482 1.7368 - 1.6941 1.6881 1.6490
Int.   2B   1.6780 1.6600   1.7037 1.6959 1.7500
Ext. 13/4-12 UN 3A 0.0000 1.7500 1.7386 - 1.6959 1.6914 1.6508
Int.   3B   1.6698 1.6600   1.7017 1.6959 1.7500
Ext. 13/4-14 UNS 2A 0.0017 1.7483 1.7380 - 1.7019 1.6963 1.6632
Int.   2B   1.6880 1.6730   1.7109 1.7036 1.7500
Ext. 13/4-16 UN 2A 0.0016 1.7484 1.7390 - 1.7078 1.7025 1.6739
Int.   2B   1.6960 1.6820   1.7163 1.7094 1.7500
Ext. 13/4-16 UN 3A 0.0000 1.7500 1.7406 - 1.7094 1.7054 1.6755
Int.   3B   1.6908 1.6820   1.7146 1.7094 1.7500
Ext. 13/4-18 UNS 2A 0.0015 1.7485 1.7398 - 1.7124 1.7073 1.6824
Int.   2B   1.7030 1.6900   1.7205 1.7139 1.7500
Ext. 13/4-20 UN 2A 0.0015 1.7485 1.7404 - 1.7160 1.7112 1.6890
Int.   2B   1.7070 1.6960   1.7238 1.7175 1.7500
Ext. 13/4-20 UN 3A 0.0000 1.7500 1.7419 - 1.7175 1.7139 1.6905
Int.   3B   1.7037 1.6960   1.7222 1.7175 1.7500
Ext. 113/16-6 UN 2A 0.0025 1.8100 1.7918 - 1.7017 1.6933 1.6116
Int.   2B   1.6630 1.6320   1.7151 1.7042 1.8125
Ext. 113/16-6 UN 3A 0.0000 1.8125 1.7943 - 1.7042 1.6979 1.6141
Int.   3B   1.6521 1.6320   1.7124 1.7042 1.8125
Ext. 113/16-8 UN 2A 0.0023 1.8102 1.7952 - 1.7290 1.7214 1.6614
Int.   2B   1.7020 1.6770   1.7412 1.7313 1.8125
Ext. 113/16-8 UN 3A 0.0000 1.8125 1.7975 - 1.7313 1.7256 1.6637
Int.   3B   1.6922 1.6770   1.7387 1.7313 1.8125
Ext. 113/16-12 UN 2A 0.0018 1.8107 1.7993 - 1.7566 1.7506 1.7115
Int.   2B   1.7400 1.7220   1.7662 1.7584 1.8125
Ext. 113/16-12 UN 3A 0.0000 1.8125 1.8011 - 1.7584 1.7539 1.7133
Int.   3B   1.7323 1.7220   1.7642 1.7584 1.8125
Ext. 113/16-16 UN 2A 0.0016 1.8109 1.8015 - 1.7703 1.7650 1.7364
Int.   2B   1.7590 1.7450   1.7788 1.7719 1.8125
Ext. 113/16-16 UN 3A 0.0000 1.8125 1.8031 - 1.7719 1.7679 1.7380
Int.   3B   1.7533 1.7450   1.7771 1.7719 1.8125
Ext. 113/16-20 UN 2A 0.0015 1.8110 1.8029 - 1.7785 1.7737 1.7515
Int.   2B   1.7700 1.7580   1.7863 1.7800 1.8125
Ext. 113/16-20 UN 3A 0.0000 1.8125 1.8044 - 1.7800 1.7764 1.7530
Int.   3B   1.7662 1.7580   1.7847 1.7800 1.8125
Ext. 17/8-6 UN 2A 0.0025 1.8725 1.8543 - 1.7642 1.7558 1.6741
Int.   2B   1.7250 1.6950   1.7777 1.7667 1.8750
Ext. 17/8-6 UN 3A 0.0000 1.8750 1.8568 - 1.7667 1.7604 1.6766
Int.   3B   1.7146 1.6950   1.7749 1.7667 1.8750
Ext. 17/8-8 UN 2A 0.0023 1.8727 1.8577 1.8502 1.7915 1.7838 1.7239
Int.   2B   1.7650 1.7400   1.8038 1.7938 1.8750
Ext. 17/8-8 UN 3A 0.0000 1.8750 1.8600 - 1.7938 1.7881 1.7262
Int.   3B   1.7547 1.7400   1.8013 1.7938 1.8750
Ext. 17/8-10 UNS 2A 0.0019 1.8731 1.8602 - 1.8081 1.8016 1.7541
Int.   2B   1.7880 1.7670   1.8184 1.8100 1.8750
Ext. 17/8-12 UN 2A 0.0018 1.8732 1.8618 - 1.8191 1.8131 1.7740
Int.   2B   1.8030 1.7850   1.8287 1.8209 1.8750
Ext. 17/8-12 UN 3A 0.0000 1.8750 1.8636 - 1.8209 1.8164 1.7758
Int.   3B   1.7948 1.7850   1.8267 1.8209 1.8750
Ext. 17/8-14 UNS 2A 0.0017 1.8733 1.8630 - 1.8269 1.8213 1.7883
Int.   2B   1.8140 1.7980   1.8359 1.8286 1.8750
Ext. 17/8-16 UN 2A 0.0016 1.8734 1.8640 - 1.8328 1.8275 1.7989
Int.   2B   1.8210 1.8070   1.8413 1.8344 1.8750
Ext. 17/8-16 UN 3A 0.0000 1.8750 1.8656 - 1.8344 1.8304 1.8005
Int.   3B   1.8158 1.8070   1.8396 1.8344 1.8750
Ext. 17/8-18 UNS 2A 0.0015 1.8735 1.8648 - 1.8374 1.8323 1.8074
Int.   2B   1.8280 1.8150   1.8455 1.8389 1.8750
Ext. 17/8-20 UN 2A 0.0015 1.8735 1.8654 - 1.8410 1.8362 1.8140
Int.   2B   1.8320 1.8210   1.8488 1.8425 1.8750
Ext. 17/8-20 UN 3A 0.0000 1.8750 1.8669 - 1.8425 1.8389 1.8155
Int.   3B   1.8287 1.8210   1.8472 1.8425 1.8750
Ext. 115/16-6 UN 2A 0.0026 1.9349 1.9167 - 1.8266 1.8181 1.7365
Int.   2B   1.7880 1.7570   1.8403 1.8292 1.9375
Ext. 115/16-6 UN 3A 0.0000 1.9375 1.9193 - 1.8292 1.8228 1.7391
Int.   3B   1.7771 1.7570   1.8375 1.8292 1.9375
Ext. 115/16-8 UN 2A 0.0023 1.9352 1.9202 - 1.8540 1.8463 1.7864
Int.   2B   1.8270 1.8020   1.8663 1.8563 1.9375
Ext. 115/16-8 UN 3A 0.0000 1.9375 1.9225 - 1.8563 1.8505 1.7887
Int.   3B   1.8172 1.8020   1.8638 1.8563 1.9375
Ext. 115/16-12 UN 2A 0.0018 1.9357 1.9243 - 1.8816 1.8755 1.8365
Int.   2B   1.8650 1.8470   1.8913 1.8834 1.9375
Ext. 115/16-12 UN 3A 0.0000 1.9375 1.9261 - 1.8834 1.8789 1.8383
Int.   3B   1.8573 1.8470   1.8893 1.8834 1.9375
Ext. 115/16-16 UN 2A 0.0016 1.9359 1.9265 - 1.8953 1.8899 1.8614
Int.   2B   1.8840 1.8700   1.9039 1.8969 1.9375
Ext. 115/16-16 UN 3A 0.0000 1.9375 1.9281 - 1.8969 1.8929 1.8630
Int.   3B   1.8783 1.8700   1.9021 1.8969 1.9375
Ext. 115/16-20 UN 2A 0.0015 1.9360 1.9279 - 1.9035 1.8986 1.8765
Int.   2B   1.8950 1.8830   1.9114 1.9050 1.9375
Ext. 115/16-20 UN 3A 0.0000 1.9375 1.9294 - 1.9050 1.9013 1.8780
Int.   3B   1.8912 1.8830   1.9098 1.9050 1.9375
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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