Inch External Threads

Unified Standard Class 2A (External)
Thread Size Thread Symbol Major Diameter Pitch Diameter UNR Minor
Diameter
Minimum Maximum Minimum Maximum Max. (Ref.)
# 6-32 UNC-2A .1312 .1372 .1141 .1169 .1000
# 8-32 UNC-2A .1571 .1631 .1399 .1428 .1259
#10-24 UNC-2A .1818 .1890 .1586 .1619 .1394
#10-32 UNF-2A .1831 .1891 .1658 .1688 .1519
1/4-20 UNC-2A .2408 .2489 .2127 .2164 .1894
1/4-28 UNF-2A .2425 .2490 .2225 .2258 .2064
5/16-18 UNC-2A .3026 .3113 .2712 .2752 .2452
5/16-24 UNF-2A .3042 .3114 .2806 .2843 .2618
3/8-16 UNC-2A .3643 .3737 .3287 .3331 .2992
3/8-24 UNF-2A .3667 .3739 .3430 .3468 .3243
1/2-13 UNC-2A .4876 .4985 .4435 .4485 .4069

Inch Internal Threads

Unified Standard Class 2B (Internal)
Thread Size Thread Symbol Minor Diameter Pitch Diameter Major
Diameter
Minimum Maximum Minimum Maximum Minimum
# 6-32 UNC-2B .104 .114 .1177 .1214 .1380
# 8-32 UNC-2B .130 .139 .1437 .1475 .1640
#10-24 UNC-2B .145 .156 .1629 .1672 .1900
#10-32 UNF-2B .156 .164 .1697 .1736 .1900
1/4-20 UNC-2B .196 .207 .2175 .2224 .2500
1/4-28 UNF-2B .211 .220 .2268 .2311 .2500
5/16-18 UNC-2B .252 .265 .2764 .2817 .3125
5/16-24 UNF-2B .267 .277 .2854 .2902 .3125
3/8-16 UNC-2B .307 .321 .3344 .3401 .3750
3/8-24 UNF-2B .330 .340 .3479 .3528 .3750
1/2-13 UNC-2B .417 .434 .4500 .4565 .5000