Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted. 2Square machine screw nuts shall have tops and bottoms flat, without chamfer. The bearing surface shall be perpendicular to the axis of the threaded hole pitch cylinder within a tolerance of 4 deg.
| Nominal Size & Threads / Inch & Series Designation | Allowance | Minor Diameter | Pitch Diameter | Major Diameter | ||||
| Min. | Max. | Min. | Max. | Tolerance | Min. | |||
| 0-80 1-64 1-72 2-56 2-64 |
UNF UNC UNF UNC UNF |
0.0005 0.0006 0.0006 0.0006 0.0006 |
0.0465 0.0561 0.0580 0.0667 0.0691 |
0.0514 0.0623 0.0635 0.0737 0.0753 |
0.0519 0.0629 0.0640 0.0744 0.0759 |
0.0542 0.0655 0.0665 0.0772 0.0786 |
0.0023 0.0026 0.0025 0.0028 0.0027 |
0.0600 0.0730 0.0730 0.0860 0.0860 |
| 3-48 3-56 4-40 4-48 5-40 |
UNC UNF UNC UNF UNC |
0.0007 0.0007 0.0008 0.0007 0.0008 |
0.0764 0.0797 0.0849 0.0894 0.0979 |
0.0845 0.0865 0.0939 0.0968 0.1062 |
0.0855 0.0874 0.0958 0.0985 0.1088 |
0.0885 0.0902 0.0991 0.1016 0.1121 |
0.0030 0.0028 0.0033 0.0031 0.0033 |
0.0990 0.0990 0.1120 0.1120 0.1250 |
| 5-44 6-32 6-40 8-32 8-36 |
UNF UNC UNF UNC UNF |
0.0007 0.0008 0.0008 0.0009 0.0008 |
0.1004 0.104 0.111 0.130 0.134 |
0.1079 0.114 0.119 0.139 0.142 |
0.1102 0.1177 0.1218 0.1437 0.1460 |
0.1134 0.1214 0.1252 0.1475 0.1496 |
0.0032 0.0037 0.0034 0.0038 0.0036 |
0.1250 0.1380 0.1380 0.1640 0.1640 |
| 10-24 10-32 12-24 12-28 1/4-20 |
UNC UNF UNC UNF UNC |
0.0010 0.0009 0.0010 0.0010 0.0011 |
0.145 0.156 0.171 0.177 0.196 |
0.156 0.164 0.181 0.186 0.207 |
0.1629 0.1697 0.1889 0.1928 0.2175 |
0.1672 0.1736 0.1933 0.1970 0.2224 |
0.0043 0.0039 0.0044 0.0042 0.0049 |
0.1900 0.1900 0.2160 0.2160 0.2500 |
| 1/4-28 5/16-18 5/16-24 3/8-16 3/8-24 |
UNF UNC UNF UNC UNF |
0.0010 0.0012 0.0011 0.0013 0.0011 |
0.211 0.252 0.267 0.307 0.330 |
0.220 0.265 0.277 0.321 0.034 |
0.2268 0.2764 0.2854 0.3344 0.3479 |
0.2311 0.2817 0.2902 0.3401 0.3528 |
0.0043 0.0053 0.0048 0.0057 0.0049 |
0.2500 0.3125 0.3125 0.3750 0.3750 |
| 7/16-14 7/16-20 1/2-13 1/2-20 9/16-12 |
UNC UNF UNC UNF UNC |
0.0014 0.0013 0.0015 0.0013 0.0016 |
0.360 0.383 0.417 0.446 0.472 |
0.376 0.395 0.434 0.457 0.490 |
0.3911 0.4050 0.4500 0.4675 0.5084 |
0.3972 0.4104 0.4565 0.4731 0.5152 |
0.0061 0.0054 0.0065 0.0056 0.0068 |
0.4375 0.4375 0.5000 0.5000 0.5625 |
| 9/16-18 5/8-11 5/8-18 3/4-10 3/4-16 |
UNF UNC UNF UNC UNF |
0.0014 0.0016 0.0014 0.0018 0.0015 |
0.502 0.527 0.565 0.642 0.682 |
0.515 0.546 0.578 0.663 0.696 |
0.5264 0.5660 0.5889 0.6850 0.7094 |
0.5323 0.5732 0.5949 0.6927 0.7159 |
0.0059 0.0072 0.0060 0.0077 0.0065 |
0.5625 0.6250 0.6250 0.7500 0.7500 |
| 7/8-9 7/8-14 1-8 1-12 1-14 |
UNC UNF UNC UNF UNS |
0.0019 0.0016 0.0020 0.0018 0.0017 |
0.755 0.798 0.865 0.910 0.923 |
0.778 0.814 0.890 0.928 0.938 |
0.8028 0.8286 0.9188 0.9459 0.9536 |
0.8110 0.8356 0.9276 0.9535 0.9609 |
0.0082 0.0070 0.0088 0.0076 0.0073 |
0.8750 0.8750 1.0000 1.0000 1.0000 |
| 11/8-7 11/8-8 11/812 11/4-7 11/4-8 |
UNC UN UNF UNC UN |
0.0022 0.0021 0.0018 0.022 0.0021 |
0.970 0.990 1.035 1.095 1.115 |
0.998 1.015 1.053 1.123 1.140 |
1.322 1.0438 1.0709 1.1572 1.1688 |
1.0416 0.0528 1.0787 1.668 1.1780 |
0.0094 0.0090 0.0078 0.0096 0.0092 |
1.1250 1.1250 1.1250 1.2500 1.2500 |
| 11/4-12 1 3/8-6 1 3/8-8 1 3/8-12 11/2-6 |
UNF UNC UN UNF UNC |
0.0018 0.0024 0.0022 0.0019 0.0024 |
1.160 1.195 1.240 1.285 1.320 |
1.178 1.225 1.265 1.303 1.350 |
1.1959 1.2667 1.2938 1.3209 1.3917 |
1.2039 1.2771 1.3031 1.3291 1.4022 |
0.0080 0.0104 0.0093 0.0082 0.0105 |
1.2500 1.3750 1.3750 1.3750 1.5000 |
| 11/2-8 11/2-12 1 5/8-8 1 3/4-5 1 3/4-8 |
UN UNC UN UNC UN |
0.0022 0.0019 0.0022 0.0027 0.0023 |
1.365 1.410 1.490 1.534 1.615 |
1.390 1.428 1.515 1.568 1.640 |
1.4188 1.4459 1.5438 1.6201 1.6688 |
1.4283 1.4542 1.5535 1.6317 1.6786 |
0.0095 0.0083 0.0097 0.0116 0.0098 |
1.5000 1.5000 1.6250 1.7500 1.7500 |
| 1 7/8-8 2-41/2 2-8 2 1/4-4.5 2 1/4-8 |
UN UNC UN UNC UN |
0.0023 0.0029 0.0023 0.0029 0.0024 |
1.740 1.759 1.865 2.009 2.115 |
1.765 1.795 1.890 2.045 2.140 |
1.7938 1.8557 1.9188 2.1057 2.1688 |
1.8038 1.8681 1.9289 2.1183 2.1792 |
0.0100 0.0124 0.0101 0.0126 0.0104 |
1.8750 2.0000 2.0000 2.2500 2.2500 |
| 2 1/2-4 2 1/2-8 2 3/4-4 2 3/4-8 3-4 |
UNC UN UNC UN UNC |
0.0031 0.0024 0.0032 0.0025 0.0032 |
2.229 2.365 2.479 2.615 2.729 |
2.267 2.390 2.517 2.640 2.767 |
2.3376 2.4188 2.5876 2.6688 2.8376 |
2.3511 2.4294 2.6013 2.6796 2.8515 |
0.0135 0.0106 0.0137 0.0108 0.0139 |
2.5000 2.5000 2.7500 2.7500 3.0000 |
| 3-8 3 1/4-4 31/4-8 3 1/2-4 31/2-8 |
UN UNC UN UNC UN |
0.0026 0.0033 0.0026 0.0033 0.0026 |
2.865 2.979 3.115 3.229 3.365 |
2.890 3.017 3.140 3.267 3.390 |
2.9188 3.0876 3.1688 3.3376 3.4188 |
2.9299 3.1017 3.1801 3.3519 3.4303 |
0.0111 0.0141 0.0113 0.0143 0.0115 |
3.0000 3.2500 3.2500 3.5000 3.5000 |
| 3 3/4-4 3 3/4-8 4-4 4-8 |
UNC UN UNC UN |
0.0034 0.0027 0.0034 0.0027 |
3.479 3.615 3.729 3.865 |
3.517 3.640 3.767 3.890 |
3.5876 3.6688 3.8376 3.9188 |
3.6021 3.6805 3.8523 3.9307 |
0.0145 0.0117 0.0147 0.0119 |
3.7500 3.7500 4.0000 4.0000 |
