US Threads Per Inch Table

Bolt Size Threads Per Inch (TPI)
Coarse Thread
UNC
Fine Thread
UNF
#0000 - 160
#000 - 120
#00 - 90
#0 - 80
#1 64 72
#2 56 64
#3 48 56
#4 40 48
#5 40 44
#6 32 40
#8 32 36
#10 24 32
#12 24 28
1/4" 20 28
5/16" 18 24
3/8" 16 24
7/16" 14 20
1/2" 13 20
9/16" 12 18
5/8" 11 18
3/4" 10 16
7/8" 9 14
1" 8 12*
1-1/8" 7 12
1-1/4" 7 12
1-1/2" 6 12
* 12tpi is the UNF standard however 14tpi is far more common in actual use.