UNIFIED SCREW THREADS1735 For UNR thread form substitute UNR for UN for external threads only Table 2 Diameter Pitch Combinations for Standard Series of Threads UN UNR Sizesa No or Inches aSizes shown in parentheses are secondary sizes Primary sizes of 41 4 41 2 43 4 5 51 4 51 2 53 4 and 6 inches also are in the 4 6 8 12 and 16 thread series secondary sizes of 41 8 43 8 45 8 47 8 51 8 53 8 55 8 and 57 8 also are in the 4 6 8 12 and 16 thread series Basic Major Dia Inches Threads per Inch Series with Graded PitchesSeries with Uniform Constant Pitches Coarse UNC Fineb UNF bFor diameters over 11 2 inches use 12 thread series Extra finec UNEF cFor diameters over 111 16 inches use 16 thread series 4 UN6 UN8 UN12 UN16 UN20 UN28 UN32 UN 00 0600 80 Series designation shown indicates the UN thread form however the UNR thread form may be specified by substituting UNR in place of UN in all designations for external threads 1 0 07306472 20 08605664 3 0 09904856 40 11204048 50 12504044 60 13803240 UNC 80 16403236 UNC 100 19002432 UNF 12 0 2160242832 UNFUNEF 1 4 0 2500202832 UNCUNFUNEF 5 16 0 3125182432 2028UNEF 3 8 0 3750162432 UNC2028UNEF 7 16 0 4375142028 16UNFUNEF32 1 2 0 5000132028 16UNFUNEF32 9 16 0 5625121824 UNC16202832 5 8 0 6250111824 1216202832 11 16 0 6875 24 1216202832 3 4 0 7500101620 12UNFUNEF2832 13 16 0 8125 20 1216UNEF2832 7 8 0 875091420 1216UNEF2832 15 16 0 9375 20 1216UNEF2832 11 000081220 UNCUNF16UNEF2832 11 16 1 0625 18 812162028 11 81 125071218 8UNF162028 13 16 1 1875 18 812162028 11 41 250071218 8UNF162028 15 161 3125 18 812162028 13 81 375061218 UNC8UNF162028 17 16 1 4375 18 6812162028 11 21 500061218 UNC8UNF162028 19 16 1 5625 18 68121620 15 81 6250 18 68121620 111 16 1 6875 18 68121620 13 41 75005 68121620 113 16 1 8125 68121620 17 81 8750 68121620 115 16 1 9375 68121620 22 000041 2 68121620 21 8 2 1250 68121620 21 42 250041 2 68121620 23 8 2 3750 68121620 21 22 50004 UNC68121620 25 8 2 6250 468121620 23 42 75004 UNC68121620 27 8 2 8750 468121620 33 00004 UNC68121620 31 8 3 1250 4681216 31 43 25004 UNC681216 33 8 3 3750 4681216 31 23 50004 UNC681216 35 8 3 6250 4681216 33 43 75004 UNC681216 37 8 3 8750 4681216 44 00004 UNC681216 Machinery s Handbook 27th Edition Copyright 2004 Industrial Press Inc New York NY UNIFIED SCREW THREADS1736 Table 3 Standard Series and Selected Combinations Unified Screw Threads Nominal Size Threads per Inch and Series Designationa ExternalbInternalb Class Allow ance Major DiameterPitch Diameter UNR Minor Dia c Max Ref Class Minor DiameterPitch Diameter Major Diameter MaxdMinMineMaxdMinMinMaxMinMaxMin 0 80 UNF2A0 00050 05950 0563 0 05140 04960 04462B0 04650 05140 05190 05420 0600 3A0 00000 06000 0568 0 05190 05060 04513B0 04650 05140 05190 05360 0600 1 64 UNC2A0 00060 07240 0686 0 06230 06030 05382B0 05610 06230 06290 06550 0730 3A0 00000 07300 0692 0 06290 06140 05443B0 05610 06230 06290 06480 0730 1 72 UNF2A0 00060 07240 0689 0 06340 06150 05592B0 05800 06350 06400 06650 0730 3A0 00000 07300 0695 0 06400 06260 05653B0 05800 06350 06400 06590 0730 2 56 UNC2A0 00060 08540 0813 0 07380 07170 06422B0 06670 07370 07440 07720 0860 3A0 00000 08600 0819 0 07440 07280 06483B0 06670 07370 07440 07650 0860 2 64 UNF2A0 00060 08540 0816 0 07530 07330 06682B0 06910 07530 07590 07860 0860 3A0 00000 08600 0822 0 07590 07440 06743B0 06910 07530 07590 07790 0860 3 48 UNC2A0 00070 09830 0938 0 08480 08250 07342B0 07640 08450 08550 08850 0990 3A0 00000 09900 0945 0 08550 08380 07413B0 07640 08450 08550 08770 0990 3 56 UNF2A0 00070 09830 0942 0 08670 08450 07712B0 07970 08650 08740 09020 0990 3A0 00000 09900 0949 0 08740 08580 07783B0 07970 08650 08740 08950 0990 4 40 UNC2A0 00080 11120 1061 0 09500 09250 08142B0 08490 09390 09580 09910 1120 3A0 00000 11200 1069 0 09580 09390 08223B0 08490 09390 09580 09820 1120 4 48 UNF2A0 00070 11130 1068 0 09780 09540 08642B0 08940 09680 09850 10160 1120 3A0 00000 11200 1075 0 09850 09670 08713B0 08940 09680 09850 10080 1120 5 40 UNC2A0 00080 12420 1191 0 10800 10540 09442B0 09790 10620 10880 11210 1250 3A0 00000 12500 1199 0 10880 10690 09523B0 09790 10620 10880 11130 1250 5 44 UNF2A0 00070 12430 1195 0 10950 10700 09722B0 10040 10790 11020 11340 1250 3A0 00000 12500 1202 0 11020 10830 09793B0 10040 10790 11020 11260 1250 6 32 UNC2A0 00080 13720 1312 0 11690 11410 10002B0 1040 1140 11770 12140 1380 3A0 00000 13800 1320 0 11770 11560 10083B0 10400 11400 11770 12040 1380 6 40 UNF2A0 00080 13720 1321 0 12100 11840 10742B0 1110 1190 12180 12520 1380 3A0 00000 13800 1329 0 12180 11980 10823B0 11100 11860 12180 12430 1380 8 32 UNC2A0 00090 16310 1571 0 14280 13990 12592B0 1300 1390 14370 14750 1640 3A0 00000 16400 1580 0 14370 14150 12683B0 13000 13890 14370 14650 1640 8 36 UNF2A0 00080 16320 1577 0 14520 14240 13012B0 1340 1420 14600 14960 1640 3A0 00000 16400 1585 0 14600 14390 13093B0 13400 14160 14600 14870 1640 Machinery s Handbook 27th Edition Copyright 2004 Industrial Press Inc New York NY UNIFIED SCREW THREADS1737 10 24 UNC2A0 00100 18900 1818 0