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UNC - 60 Degree Unified Coarse Threads

UNC Thread Series / UNRC are the one most commonly used in the bulk production of bolts, screws, nuts and other general engineering applications. It is also used for threading into lower tensile strength materials such as cast iron, mild steel and softer materials (bronze, brass, aluminum, magnesium and plastics) to obtain the optimum resistance to stripping of the internal thread. It is applicable for rapid assembly or disassembly, or if corrosion or slight damage is possible.

#1- #12 1/4" - 9/16" 5/8" - 1 3/8" 1 3/4" - 3" 3 1/4" - 4"

UNC Threads



Nominal Size External (b) Internal (b)
Threads per Inch and Series Designation Class Allowance Major Diameter Minor Diameter UNR Minor Dia.,c Max (Ref.) Class Minor Diameter Pitch Diameter Major Diameter
Max (d) Min Min (e) Max (d) Min Min Max Min Max Min
#1 - 64UNC 2A 0.0006 1.839 1.742 . . . 1.582 1.532 1.367 2B 1.425 1.582 1.598 1.664 1.854
#1 - 64UNC 3A 0 1.854 1.758 . . . 1.598 1.56 1.382 3B 1.425 1.582 1.598 1.646 1.854
#2 - 56UNC 2A 0.0006 2.169 2.065 . . . 1.875 1.821 1.631 2B 1.694 1.872 1.89 1.961 2.184
#2 - 56UNC 3A 0 2.184 2.08 . . . 1.89 1.849 1.646 3B 1.694 1.872 1.89 1.943 2.184
#3 - 48UNC 2A 0.0007 2.497 2.383 . . . 2.154 2.096 1.864 2B 1.941 2.146 2.172 2.248 2.515
#3 - 48UNC 3A 0 2.515 2.4 . . . 2.172 2.129 1.882 3B 1.941 2.146 2.172 2.228 2.515
#4 - 40UNC 2A 0.0008 2.824 2.695 . . . 2.413 2.35 2.068 2B 2.156 2.385 2.433 2.517 2.845
#4 - 40UNC 3A 0 2.845 2.715 . . . 2.433 2.385 2.088 3B 2.156 2.385 2.433 2.494 2.845
#5 - 40UNC 2A 0.0008 3.155 3.025 . . . 2.743 2.677 2.398 2B 2.487 2.697 2.764 2.847 3.175
#5 - 40UNC 3A 0 3.175 3.045 . . . 2.764 2.715 2.418 3B 2.487 2.697 2.764 2.827 3.175
#6 - 32UNC 2A 0.0008 3.485 3.332 . . . 2.969 2.898 2.54 2B 2.642 2.896 2.99 3.084 3.505
#6 - 32UNC 3A 0 3.505 3.353 . . . 2.99 2.936 2.56 3B 2.642 2.896 2.99 3.058 3.505
#8 - 32UNC 2A 0.0009 4.143 3.99 . . . 3.627 3.553 3.198 2B 3.302 3.531 3.65 3.747 4.166
#8 - 32UNC 3A 0 4.166 4.013 . . . 3.65 3.594 3.221 3B 3.302 3.528 3.65 3.721 4.166
#10 - 24UNC 2A 0.001 4.801 4.618 . . . 4.112 4.028 3.541 2B 3.683 3.962 4.138 4.247 4.826
#10 - 24UNC 3A 0 4.826 4.643 . . . 4.138 4.074 3.566 3B 3.683 3.95 4.138 4.219 4.826
#12 - 24UNC 2A 0.001 5.461 5.278 . . . 4.773 4.686 4.201 2B 4.343 4.597 4.798 4.91 5.486
#12 - 24UNC 3A 0 5.486 5.304 . . . 4.798 4.732 4.227 3B 4.343 4.59 4.798 4.882 5.486
1/4" - 20UNC 1A 0.0011 6.322 6.012 . . . 5.497 5.354 4.811 1B 4.978 5.258 5.525 5.71 6.35
1/4" - 20UNC 2A 0.0011 6.322 6.116 6.012 5.497 5.403 4.811 2B 4.978 5.258 5.525 5.649 6.35
1/4" - 20UNC 3A 0 6.35 6.144 . . . 5.525 5.453 4.839 3B 4.978 5.25 5.525 5.616 6.35
5/16" - 18UNC 1A 0.0012 7.907 7.574 . . . 6.99 6.835 6.228 1B 6.401 6.731 7.021 7.221 7.938
5/16" - 18UNC 2A 0.0012 7.907 7.686 7.574 6.99 6.888 6.228 2B 6.401 6.731 7.021 7.155 7.938
5/16" - 18UNC 3A 0 7.938 7.717 . . . 7.021 6.944 6.259 3B 6.401 6.68 7.021 7.12 7.938
3/8" - 16UNC 1A 0.0013 9.492 9.131 . . . 8.461 8.296 7.6 1B 7.798 8.153 8.494 8.71 9.525
3/8" - 16UNC 2A 0.0013 9.492 9.253 9.131 8.461 8.349 7.6 2B 7.798 8.153 8.494 8.639 9.525
3/8" - 16UNC 3A 0 9.525 9.286 . . . 8.494 8.41 7.633 3B 7.798 8.082 8.494 8.603 9.525
7/16" - 14UNC 1A 0.0014 11.077 10.683 . . . 9.898 9.718 8.918 1B 9.144 9.55 9.934 10.168 11.113
7/16" - 14UNC 2A 0.0014 11.077 10.815 10.683 9.898 9.779 8.918 2B 9.144 9.55 9.934 10.089 11.113
7/16" - 14UNC 3A 0 11.113 10.851 . . . 9.934 9.845 8.954 3B 9.144 9.441 9.934 10.051 11.113
1/2" - 13UNC 1A 0.0015 12.662 12.248 . . . 11.392 11.204 10.335 1B 10.592 11.024 11.43 11.676 12.7
1/2" - 13UNC 2A 0.0015 12.662 12.385 12.248 11.392 11.265 10.335 2B 10.592 11.024 11.43 11.595 12.7
1/2" - 13UNC 3A 0 12.7 12.423 . . . 11.43 11.336 10.373 3B 10.592 10.881 11.43 11.552 12.7
9/16" - 12UNC 1A 0.0016 14.247 13.81 . . . 12.873 12.675 11.727 1B 11.989 12.446 12.913 13.172 14.288
9/16" - 12UNC 2A 0.0016 14.247 13.957 13.81 12.873 12.741 11.727 2B 11.989 12.446 12.913 13.086 14.288
9/16" - 12UNC 3A 0 14.288 13.998 . . . 12.913 12.814 11.768 3B 11.989 12.301 12.913 13.043 14.288
5/8" - 11UNC 1A 0.0016 15.834 15.372 . . . 14.336 14.125 13.086 1B 13.386 13.868 14.376 14.648 15.875
5/8" - 11UNC 2A 0.0016 15.834 15.527 15.372 14.336 14.196 13.086 2B 13.386 13.868 14.376 14.559 15.875
5/8" - 11UNC 3A 0 15.875 15.568 . . . 14.376 14.272 13.127 3B 13.386 13.693 14.376 14.514 15.875
3/4" - 10UNC 1A 0.0018 19.004 18.512 . . . 17.353 17.13 15.979 1B 16.307 16.84 17.399 17.691 19.05
3/4" - 10UNC 2A 0.0018 19.004 18.677 18.512 17.353 17.203 15.979 2B 16.307 16.84 17.399 17.595 19.05
3/4" - 10UNC 3A 0 19.05 18.722 . . . 17.399 17.287 16.025 3B 16.307 16.624 17.399 17.544 19.05
7/8" - 9UNC 1A 0.0019 22.177 21.648 . . . 20.343 20.102 18.816 1B 19.177 19.761 20.391 20.704 22.225
7/8" - 9UNC 2A 0.0019 22.177 21.824 21.648 20.343 20.183 18.816 2B 19.177 19.761 20.391 20.599 22.225
7/8" - 9UNC 3A 0 22.225 21.872 . . . 20.391 20.272 18.865 3B 19.177 19.51 20.391 20.546 22.225
1" - 8UNC 1A 0.002 25.349 24.778 . . . 23.287 23.03 21.57 1B 21.971 22.606 23.338 23.673 25.4
1" - 8UNC 2A 0.002 25.349 24.968 24.778 23.287 23.114 21.57 2B 21.971 22.606 23.338 23.561 25.4
1" - 8UNC 3A 0 25.4 25.019 . . . 23.338 23.208 21.62 3B 21.971 22.344 23.338 23.505 25.4
1 1/8" - 7UNC 1A 0.0022 28.519 27.894 . . . 26.162 25.885 24.199 1B 24.638 25.349 26.218 26.576 28.575
1 1/8" - 7UNC 2A 0.0022 28.519 28.103 27.894 26.162 25.979 24.199 2B 24.638 25.349 26.218 26.457 28.575
1 1/8" - 7UNC 3A 0 28.575 28.158 . . . 26.218 26.081 24.254 3B 24.638 25.083 26.218 26.398 28.575
1 1/4" - 7UNC 1A 0.0022 31.694 31.069 . . . 29.337 29.055 27.374 1B 27.813 28.524 29.393 29.759 31.75
1 1/4" - 7UNC 2A 0.0022 31.694 31.278 31.069 29.337 29.149 27.374 2B 27.813 28.524 29.393 29.637 31.75
1 1/4" - 7UNC 3A 0 31.75 31.333 . . . 29.393 29.253 27.429 3B 27.813 28.258 29.393 29.576 31.75
1 3/8" - 6UNC 1A 0.0024 34.864 34.171 . . . 32.113 31.808 29.825 1B 30.353 31.115 32.174 32.568 34.925
1 3/8" - 6UNC 2A 0.0024 34.864 34.402 34.171 32.113 31.91 29.825 2B 30.353 31.115 32.174 32.438 34.925
1 3/4" - 5UNC 1A 0.0027 44.381 43.599 . . . 41.082 40.742 38.334 1B 38.964 39.827 41.151 41.593 44.45
1 3/4" - 5UNC 2A 0.0027 44.381 43.861 43.599 41.082 40.856 38.334 2B 38.964 39.827 41.151 41.445 44.45
1 3/4" - 5UNC 3A 0 44.45 43.929 . . . 41.151 40.98 38.402 3B 38.964 39.561 41.151 41.372 44.45
2" - 4 1/2UNC 1A 0.0029 50.726 49.888 . . . 47.061 46.698 44.003 1B 44.679 45.593 47.135 47.607 50.8
2" - 4 1/2UNC 2A 0.0029 50.726 50.168 49.888 47.061 46.82 44.003 2B 44.679 45.593 47.135 47.45 50.8
2" - 4 1/2UNC 3A 0 50.8 50.241 . . . 47.135 46.954 44.077 3B 44.679 45.367 47.135 47.371 50.8
2 1/4" - 4 1/2UNC 1A 0.0029 57.076 56.238 . . . 53.411 53.04 50.353 1B 51.029 51.943 53.485 53.967 57.15
2 1/4" - 4 1/2UNC 2A 0.0029 57.076 56.518 56.238 53.411 53.165 50.353 2B 51.029 51.943 53.485 53.805 57.15
2 1/4" - 4 1/2UNC 3A 0 57.15 56.591 . . . 53.485 53.299 50.427 3B 51.029 51.943 53.485 53.726 57.15
2 1/2" - 4UNC 1A 0.0031 63.421 62.514 . . . 59.296 58.903 55.86 1B 56.617 57.582 59.375 59.888 63.5
2 1/2" - 4UNC 2A 0.0031 63.421 62.817 62.514 59.296 59.032 55.86 2B 56.617 57.582 59.375 59.718 63.5
2 1/2" - 4UNC 3A 0 63.5 62.895 . . . 59.375 59.177 55.938 3B 56.617 57.389 59.375 59.632 63.5
2 3/4" - 4UNC 1A 0.0032 69.769 68.862 . . . 65.644 65.242 62.207 1B 62.967 63.932 65.725 66.248 69.85
2 3/4" - 4UNC 2A 0.0032 69.769 69.164 68.862 65.644 65.377 62.207 2B 62.967 63.932 65.725 66.073 69.85
2 3/4" - 4UNC 3A 0 69.85 69.245 . . . 65.725 65.524 62.288 3B 62.967 63.739 65.725 65.987 69.85
3" - 4UNC 1A 0.0032 76.119 75.212 . . . 71.994 71.585 68.557 1B 69.317 70.282 72.075 72.606 76.2
3" - 4UNC 2A 0.0032 76.119 75.514 75.212 71.994 71.722 68.557 2B 69.317 70.282 72.075 72.428 76.2
3" - 4UNC 3A 0 76.2 75.595 . . . 72.075 71.872 68.638 3B 69.317 70.089 72.075 72.339 76.2
3 1/4" - 4UNC 1A 0.0033 82.466 81.559 . . . 78.341 77.927 74.905 1B 75.667 76.632 78.425 78.964 82.55
3 1/4" - 4UNC 2A 0.0033 82.466 81.862 81.559 78.341 78.064 74.905 2B 75.667 76.632 78.425 78.783 82.55
3 1/4" - 4UNC 3A 0 82.55 81.945 . . . 78.425 78.217 74.988 3B 75.667 76.439 78.425 78.694 82.55
3 1/2" - 4UNC 1A 0.0033 88.816 87.909 . . . 84.691 84.27 81.255 1B 82.017 82.982 84.775 85.321 88.9
3 1/2" - 4UNC 2A 0.0033 88.816 88.212 87.909 84.691 84.412 81.255 2B 82.017 82.982 84.775 85.138 88.9
3 1/2" - 4UNC 3A 0 88.9 88.295 . . . 84.775 84.564 81.338 3B 82.017 82.789 84.775 85.049 88.9
3 3/4" - 4UNC 1A 0.0034 95.164 94.257 . . . 91.039 90.612 87.602 1B 88.367 89.332 91.125 91.679 95.25
3 3/4" - 4UNC 2A 0.0034 95.164 94.559 94.257 91.039 90.754 87.602 2B 88.367 89.332 91.125 91.493 95.25
3 3/4" - 4UNC 3A 0 95.25 94.645 . . . 91.125 90.912 87.688 3B 88.367 89.139 91.125 91.402 95.25
4" - 4UNC 1A 0.0034 101.514 100.607 . . . 97.389 96.957 93.952 1B 94.717 95.682 97.475 98.036 101.6
4" - 4UNC 2A 0.0034 101.514 100.909 100.607 97.389 97.102 93.952 2B 94.717 95.682 97.475 97.848 101.6
4" - 4UNC 3A 0 101.6 100.995 . . . 97.475 97.259 94.038 3B 94.717 95.489 97.475 97.757 101.6