Toggle Menu MENU
Free Standard Shipping* *In the Continental US
888-660-0334 Mon-Fri 8:00AM-5:00PM CST

Bolt & Screw Thread Lengths

 

Imperial (inch)
Thread Length Chart

Diameter
(Inch)
Nominal Thread Length
Less Than 6"
Nominal Thread Length
Greater Than 6"
A325 & A490
Thread Length
1/4" 0.75 1.00  
5/16" 0.875 1.125  
3/8" 1.00 1.25  
7/16" 1.125 1.375  
1/2" 1.25 1.5 1
9/16" 1.375 1.625  
5/8" 1.5 1.75 1.25
3/4" 1.75 2 1.375
7/8" 2 2.25 1.5
1" 2.25 2.5 1.75
1-1/8" 2.5 2.75 2
1-1/4" 2.75 3 2
1-3/8" 3 3.25 2.25
1-1/2" 3.25 3.5 2.25
1-3/4" 3.75 4  
2" 4.25 4.5  
2-1/4" 4.75 5  
2-1/2" 5.25 5.5  
2-3/4" 5.75 6  
3" 6.25 6.5  
3-1/4" 6.75 7  
3-1/2" 7.25 7.5  
3-3/4" 7.75 8  
4" 8.25 8.5  

 

Metric Standard Thread Length for Bolts

Bolt Diameter
(mm)
Standard Thead Length (mm) *
Bolts 125mm and shorterBolts longer than 125mm
3 12 -
4 14 -
5 16 22
6 18 24
7 20 26
8 22 28
10 26 32
12 30 36
14 34 40
16 38 44
18 42 48
20 46 52
* Important note: Some bolts may vary from the standard thread length.

Trying to make sense of all the different screw and bolt thread lengths can be a real challenge—even for the most knowledgeable of professionals. Are you finding yourself a little confused, or do you need a quick refresher? Never let thread length get the best of you with our help from ASMC. We’ve put together a handy thread length chart that is certain to make quick work of confusion and increase work production.