Engineer's
Handbook
 
Reference Tables
 
Rapid
Prototyping
 
Manufacturing
Methods
 
Engineering
Materials
 
Engineering
Software
 
Reference Books
 
Mechanical
Components
 

Reference Tables -- UNC / UNF Threads per Inch (TPI)

 

Thread Count (TPI) Explained - TPI stands for Threads Per Inch which is simply a count of the number of threads per inch measured along the length of a fastener. This description is used only with American fasteners. Metric Fasteners use a thread Pitch to designate different thread sizes.

 

Bolt Size
No. or Inches
Threads Per Inch (TPI)
Coarse Thread
UNC
Fine Thread
UNF
#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
1-3/8
6
12
1-1/2
6
12
1-3/4 5  
2 4-1/2  
2-1/4 4-1/2  
2-1/2 4  
2-3/4 4  
3 4  
3-1/4 4  
3-1/2 4  
3-3/4 4  
4 4  



 

 

 

 

 

 

 


Copyright © 2004 - 2006 -- EngineersHandbook.com

All Rights Reserved - Contact Information
Privacy Policy
Disclaimer