UNC THREAD CHART

UNC thread chart including major diameter, pitch diameter and minor diameter dimensions of UNC screw threads according to ASME B1.1 standard.

External Thread Dimensions for UNC Screw Threads:

UNC Thread Chart — External Thread Dimensions
Nominal
Diameter		 TPI Tolerance
Class		 Major Dia. Pitch Dia. Max.
Minor
Diameter
max. min. max. min.
#1 - 64 64 2A 0.0724 0.0686 0.0623 0.0603 0.0538
#2 - 56 56 2A 0.0854 0.0813 0.0738 0.0717 0.0642
#3 - 48 48 2A 0.0983 0.0938 0.0848 0.0825 0.0734
#4- 40 40 2A 0.1112 0.1061 0.0950 0.0925 0.0814
#5 - 40 40 2A 0.1242 0.1191 0.1080 0.1054 0.0944
#6 - 32 32 2A 0.1372 0.1312 0.1169 0.1141 0.1000
#8 - 32 32 2A 0.1631 0.1571 0.1428 0.1399 0.1259
#10 - 24 24 2A 0.1890 0.1818 0.1619 0.1586 0.1394
#12 - 24 24 2A 0.2150 0.2078 0.1879 0.1845 0.1654
1/4” - 20 20 2A 0.2489 0.2408 0.2164 0.2127 0.1894
5/16" - 18 18 2A 0.3113 0.3026 0.2752 0.2712 0.2452
3/8" - 16 16 2A 0.3737 0.3643 0.3331 0.3287 0.2992
7/16" - 14 14 2A 0.4361 0.4258 0.3897 0.3850 0.3511
1/2" - 13 13 2A 0.4985 0.4876 0.4485 0.4435 0.4069
Nominal
Diameter		 TPI Tolerance
Class		 Major Dia. Pitch Dia. Max.
Minor
Diameter
max. min. max. min.
9/16" - 12 12 2A 0.5609 0.5495 0.5068 0.5016 0.4617
5/8" - 11 11 2A 0.6234 0.6113 0.5644 0.5589 0.5152
3/4" - 10 10 2A 0.7482 0.7353 0.6832 0.6773 0.6291
7/8" - 9 9 2A 0.8731 0.8592 0.8009 0.7946 0.7408
1" - 8 8 2A 0.9980 0.9830 0.9168 0.9100 0.8492
1 1/8" - 7 7 2A 1.1228 1.1064 1.0300 1.0228 0.9527
1 1/4" - 7 7 2A 1.2478 1.2314 1.1550 1.1476 1.0777
1 3/8" - 6 6 2A 1.3726 1.3544 1.2643 1.2563 1.1742
1 1/2" - 6 6 2A 1.4976 1.4794 1.3893 1.3812 1.2992
1 3/4" - 5 5 2A 1.7473 1.7268 1.6174 1.6085 1.5092
2" - 4 1/2 4.5 2A 1.9971 1.9751 1.8528 1.8433 1.7324
2 1/4" - 4 1/2 4.5 2A 2.2471 2.2251 2.1028 2.0931 1.9824
2 1/2" - 4 4 2A 2.4969 2.4731 2.3345 2.3241 2.1992
2 3/4" - 4 4 2A 2.7468 2.7230 2.5844 2.5739 2.4491
3" - 4 4 2A 2.9968 2.9730 2.8344 2.8237 2.6991
3 1/4" - 4 4 2A 3.2467 3.2229 3.0843 3.0734 2.9490
3 1/2" - 4 4 2A 3.4967 3.4729 3.3343 3.3233 3.1990
3 3/4" - 4 4 2A 3.7466 3.7228 3.5842 3.5730 3.4489
4" - 4 4 2A 3.9966 3.9728 3.8342 3.8229 3.6989
Nominal
Diameter		 TPI Tolerance
Class		 max. min. max. min. Max.
Minor
Diameter
Major Dia. Pitch Dia.
 

Internal Thread Dimensions for UNC Screw Threads:

UNC Thread Chart — Internal Thread Dimensions
Nominal
Diameter		 TPI Tolerance
Class		 Major Dia. Pitch Dia. Minor Dia.
min. max. min. max.  min
#1 - 64 64 2B 0.0730 0.0655 0.0629 0.0623 0.0561
#2 - 56 56 2B 0.0860 0.0772 0.0744 0.0737 0.667
#3 - 48 48 2B 0.0990 0.0855 0.0855 0.0845 0.0764
#4- 40 40 2B 0.1120 0.0991 0.0958 0.0939 0.0849
#5 - 40 40 2B 0.1250 0.1121 0.1088 0.1062 0.0979
#6 - 32 32 2B 0.1380 0.1214 0.1177 0.1140 0.1040
#8 - 32 32 2B 0.1640 0.1475 0.1437 0.1390 0.1300
#10 - 24 24 2B 0.1900 0.1672 0.1629 0.1560 0.1450
#12 - 24 24 2B 0.2160 0.1933 0.1889 0.1810 0.1710
1/4” - 20 20 2B 0.2500 0.2224 0.2175 0.2070 0.1960
5/16" - 18 18 2B 0.3125 0.2817 0.2764 0.2650 0.2520
3/8" - 16 16 2B 0.3750 0.3401 0.3344 0.3210 0.3070
7/16" - 14 14 2B 0.4375 0.3972 0.3911 0.3760 0.3600
1/2" - 13 13 2B 0.5000 0.4565 0.4500 0.4340 0.4170
Nominal
Diameter		 TPI Tolerance
Class		 Major Dia. Pitch Dia. Minor Dia.
min. max. min. max. min.
9/16" - 12 12 2B 0.5625 0.5125 0.5084 0.4900 0.4720
5/8" - 11 11 2B 0.6250 0.5732 0.5660 0.5460 0.5270
3/4" - 10 10 2B 0.7500 0.6927 0.6850 0.6630 0.6420
7/8" - 9 9 2B 0.8750 0.8110 0.8028 0.7780 0.7550
1" - 8 8 2B 1.0000 0.9276 0.9188 0.8900 0.8650
1 1/8" - 7 7 2B 1.1250 1.0416 1.0322 0.9980 0.9700
1 1/4" - 7 7 2B 1.2500 1.1668 1.1572 1.1230 1.0950
1 3/8" - 6 6 2B 1.3750 1.2771 1.2667 1.2250 1.1950
1 1/2" - 6 6 2B 1.5000 1.4075 1.3917 1.3500 1.3200
1 3/4" - 5 5 2B 1.7500 1.6317 1.6201 1.5680 1.5340
2" - 4 1/2 4.5 2B 2.0000 1.8681 1.8557 1.7950 1.7590
2 1/4" - 4 1/2 4.5 2B 2.2500 2.1183 2.1057 2.0450 2.0090
2 1/2" - 4 4 2B 2.5000 2.3511 2.3376 2.2670 2.2290
2 3/4" - 4 4 2B 2.7500 2.6013 2.5876 2.5170 2.4790
3" - 4 4 2B 3.0000 2.8515 2.8376 2.7670 2.7290
3 1/4" - 4 4 2B 3.2500 3.1017 3.0876 3.0170 2.9790
3 1/2" - 4 4 2B 3.5000 3.3519 3.3376 3.2670 3.2290
3 3/4" - 4 4 2B 3.7500 3.6021 3.5876 3.5170 3.4790
4" - 4 4 2B 4.0000 3.8523 3.8376 3.7670 3.7290
Nominal
Diameter		 TPI Tolerance
Class		 min. max. min. max. min.
Major Dia. Pitch Dia. Minor Dia.

General Note: All dimensions expressed in inches.

Supplements:

Reference:

  • ASME B1.1-2003, Unified Inch Screw Threads (UN and UNR Thread Form)
  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) . Machinery's Handbook . 30th edition.  Industrial Press Inc.
  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2012) . Machinery's Handbook . 29th edition.  Industrial Press Inc.