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UNF THREAD CHART

UN Thread Calculator UNC thread chart UNF thread chart Unified thread standard 3‑wire sizes (UN)

UNF thread chart according to ASME B1.1 standard.

UNF Thread Chart — External Thread Dimensions
Nominal
Diameter		 TPI Tolerance
Class		 Major Dia. Pitch Dia. Max.
Minor
Diameter
max. min. max. min.
#0 - 80 80 2A 0.0595 0.0563 0.0514 0.0496 0.0446
#1 - 72 72 2A 0.0724 0.0689 0.0634 0.0615 0.0559
#2 - 64 64 2A 0.0854 0.0816 0.0753 0.0733 0.0668
#3 - 56 56 2A 0.0983 0.0942 0.0867 0.0845 0.0771
#4 - 48 48 2A 0.1113 0.1068 0.0979 0.0954 0.0864
#5 - 44 44 2A 0.1243 0.1195 0.1095 0.1070 0.0972
#6 - 40 40 2A 0.1372 0.1321 0.1210 0.1184 0.1074
#8 - 36 36 2A 0.1632 0.1577 0.1452 0.1424 0.1301
#10 - 32 32 2A 0.1891 0.1831 0.1688 0.1658 0.1519
#12 - 28 28 2A 0.2150 0.2085 0.1918 0.1886 0.1724
1/4" - 28 28 2A 0.2490 0.2425 0.2258 0.2225 0.2064
5/16" - 24 24 2A 0.3114 0.3042 0.2843 0.2806 0.2618
3/8" - 24 24 2A 0.3739 0.3667 0.3468 0.3430 0.3243
7/16" - 20 20 2A 0.4362 0.4281 0.4037 0.3995 0.3767
Nominal
Diameter		 TPI Tolerance
Class		 Major Dia. Pitch Dia. Max.
Minor
Diameter
max. min. max. min.
1/2" - 20 20 2A 0.4987 0.4906 0.4662 0.4619 0.4392
9/16" - 18 18 2A 0.5611 0.5524 0.5250 0.5205 0.4950
5/8" - 18 18 2A 0.6236 0.6149 0.5875 05828 0.5575
3/4" - 16 16 2A 0.7485 0.7391 0.7079 0.7029 0.6740
7/8" - 14 14 2A 0.8734 0.8631 0.8270 0.8216 0.7884
1" - 12 12 2A 0.9982 0.9868 0.9441 0.9382 0.8990
1 1/8" - 12 12 2A 1.1232 1.1118 1.0691 1.0631 1.0240
1 1/4" - 12 12 2A 1.2482 1.2368 1.1941 1.1879 1.4190
1 3/8" - 12 12 2A 1.3731 1.3617 1.3190 1.3127 1.2739
1 1/2" - 12 12 2A 1.4981 1.4867 1.4440 1.4376 1.3989
Nominal
Diameter		 TPI Tolerance
Class		 max. min. max. min. Max.
Minor
Diameter
Major Dia. Pitch Dia.
 
UNF Thread Chart — Internal Thread Dimensions
Nominal
Diameter		 TPI Tolerance
Class		 Major Dia. Pitch Dia. Minor Dia.
min. max. min. max.  min
#0 - 80 80 2B 0.0600 0.0542 0.0519 0.0514 0.0465
#1 - 72 72 2B 0.0730 0.0665 0.0640 0.0635 0.0580
#2 - 64 64 2B 0.0860 0.0786 0.0759 0.0753 0.0691
#3 - 56 56 2B 0.0990 0.0902 0.0874 0.0865 0.0797
#4 - 48 48 2B 0.1120 0.1016 0.0985 0.0968 0.0894
#5 - 44 44 2B 0.1250 0.1134 0.1102 0.1079 0.1004
#6 - 40 40 2B 0.1380 0.1252 0.1218 0.1190 0.1110
#8 - 36 36 2B 0.1640 0.1496 0.1460 0.1420 0.1340
#10 - 32 32 2B 0.1900 0.1736 0.1697 0.1640 0.1560
#12 - 28 28 2B 0.2160 0.1970 0.1928 0.1860 0.1770
1/4" - 28 28 2B 0.2500 0.2333 0.2268 0.2200 0.2110
5/16" - 24 24 2B 0.3125 0.2925 0.2854 0.2770 0.2670
3/8" - 24 24 2B 0.3750 0.3553 0.3479 0.3400 0.3300
7/16" - 20 20 2B 0.4375 0.4131 0.4050 0.3950 0.3830
Nominal
Diameter		 TPI Tolerance
Class		 Major Dia. Pitch Dia. Minor Dia.
min. max. min. max. min.
1/2" - 20 20 2B 0.5000 0.4731 0.4675 0.4570 0.4460
9/16" - 18 18 2B 0.5625 0.5323 0.5264 0.5150 0.5020
5/8" - 18 18 2B 0.5625 0.5949 0.5889 0.5780 0.5650
3/4" - 16 16 2B 0.7500 0.7159 0.7094 0.6960 0.6820
7/8" - 14 14 2B 0.8750 0.8356 0.8266 0.8140 0.7980
1" - 12 12 2B 1.0000 0.9535 0.9459 0.9280 0.9100
1 1/8" - 12 12 2B 1.1250 1.0787 1.0709 1.0530 1.0350
1 1/4" - 12 12 2B 1.2500 1.2039 1.1959 1.1780 1.1600
1 3/8" - 12 12 2B 1.3750 1.3291 1.3209 1.3030 1.2850
1 1/2" - 12 12 2B 1.5000 1.4542 1.4459 1.4280 1.4100
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.