Imperial Hex Head Bolt Specifications
![](https://d1mv2b9v99cq0i.cloudfront.net/eyJidWNrZXQiOiJ3ZWItbmluamEtaW1hZ2VzIiwia2V5IjoiMzE2ZGlzdHJpYnV0aW9uXC9jb250ZW50LWltYWdlXC9ESEVYQk9MVC0xLmpwZyIsImVkaXRzIjp7InJlc2l6ZSI6eyJ3aWR0aCI6MzYzLCJoZWlnaHQiOjE0NiwiZml0IjoiaW5zaWRlIn19LCJ2ZXJzaW9uIjoiIn0=)
- B Measurement varies according to the length of bolt
- All measurements are in millimeters (mm)
- For Hex Set Screws disregard B measurement as they are fully threaded
ANSI B18.2.1 Specifications
D |
B to 6" |
B over 6" |
K |
S |
1/4 |
19.05 |
25.4 |
4.14 |
11.13 |
5/16 |
22.22 |
28.57 |
5.36 |
12.70 |
3/8 |
25.4 |
31.75 |
6.17 |
14.27 |
7/16 |
28.57 |
34.9 |
7.39 |
15.90 |
1/2 |
31.75 |
38.1 |
8.20 |
19.05 |
5/8 |
38.1 |
44.5 |
10.24 |
23.83 |
3/4 |
44.45 |
50.8 |
12.27 |
28.58 |
7/8 |
50.8 |
57.15 |
14.30 |
33.32 |
1" |
57.15 |
63.50 |
15.92 |
38.1 |
BS1083 Specifications
D |
B to 6" |
B over 6" |
K |
S |
1/4 |
19.05 |
25.4 |
4 |
10 |
5/16 |
22.24 |
28.57 |
5 |
12 |
3/8 |
25.4 |
31.75 |
5.55 |
14 |
7/16 |
28.57 |
34.93 |
7 |
17 |
1/2 |
31.75 |
38.1 |
7.65 |
19 |
5/8 |
38.10 |
44.5 |
9.35 |
23 |
* Use this information as a guide only