Thread Pitch
(For Bolts and Screws that take Nuts)
(US Standard)

Size Major Dia Threads Per Inch Threads Per Inch Threads Per Inch
# inch UNC/USS UNF/SAE UN8/UNS
#0000 n/a 120 160 N/A
#000 n/a 96 120 N/A
#00 n/a 80 96 N/A
#0 0.060 72 80 N/A
#1 0.073 64 72 N/A
#2 0.086 56 64 N/A
#3 0.099 48 56 N/A
#4 0.112 40 48 N/A
#5 0.125 40 44 N/A
#6 0.138 32 40 N/A
#8 0.164 32 36 N/A
#10 0.19 24 32 N/A
#12 0.216 24 28 N/A
1/4 0.25 20 28 N/A
5/16 0.3125 18 24 N/A
3/8 0.375 16 24 N/A
7/16 0.4375 14 20 N/A
1/2 0.5 13 20 N/A
9/16 0.5625 12 18 N/A
5/8 0.625 11 18 N/A
3/4 0.75 10 16 N/A
7/8 0.875 9 14 N/A
1 1 8 14 (12) 8
11/8 1.125 7 12 8
11/4 1.25 7 12 8
13/8 1.375 6 12 8
11/2 1.5 6 12 8
15/8 1.625 5.5 12 8
13/4 1.75 5 12 8
17/8 1.875 5 12 8
2 2 4.5 12 8
21/4 2.25 4.5 12 8
21/2 2.5 4 12 8
23/4 2.75 4 12 8
3 3 4 12 8
31/4 3.25 4 12 8
31/2 3.5 4 12 8
33/4 3.75 4 12 8
4 4 4 12 8

Thread Pitch
(for Tapping Screws)

and
Size Major Dia Threads Per Inch Threads Per Inch
# inch "A"* "B" and "AB"
#0 0.060 40 48
#1 0.073 32 42
#2 0.086 32 32
#3 0.099 28 28
#4 0.112 24 24
#5 0.125 20 20
#6 0.138 18 20
#7 0.164 16 19
#8 0.164 15 18
#10 0.19 12 16
#12 0.216 11 14
1/4 (#14) 0.25 10 14
5/16 (#20) 0.3125 9 12
3/8 (#24) 0.375 9 12

* Many diameters Wood Screws also have the same TPI as Tapping Screws.

 

 

 

This page last updated 10 May 2008.