Bolt Thread Size Guide
Determining the correct bolt size is crucial for achieving project success. The right bolt will ensure that your project performs as designed with optimal functionality. Additionally, the correct fastener will reinforce project security and ensure safety for all involved. Applications with the proper fasteners ensure reliability and consistency for all projects, no matter the industry.
Understanding bolt threading will help determine which bolt offers the best solution for your project. As leaders in the bolt-threading industry, Oster is prepared to assist you with any questions and guide you to ideal results. Contact Oster today to learn more.
Measuring Bolts & Bolt Threads
Determining the correct bolt requires an understanding of fastener sizes and measurements. The size of a bolt is determined by the diameter of the bolt’s shank, which is separate from the bolt head. Bolt diameter is commonly separated into three categories:
- Major diameter: The largest and most outer diameter of a bolt’s shank.
- Pitch diameter: The diameter where the thread thickness equals the space between the threads.
- Minor diameter: The smallest and most interior diameter of a bolt’s shank.
Bolt Thread Size Chart
The following bolt thread size chart includes dimensions of common bolt sizes. Each bolt size includes information about UNC and UNF threading, with UNC thread specifications on the top and UNF details below. Class 2A is acceptable for many applications and Unified Thread Standard (UTS) bolt classes.
|
Size |
Threads Per Inch |
Class Thread |
Major Diameter Min Max |
Pitch Diameter Min Max |
Minor Diameter |
||
|
1/4 |
20 |
2A |
0.2489 |
0.2408 |
0.2164 |
0.2127 |
0.1876 |
|
28 |
2A |
0.2490 |
0.2425 |
0.2258 |
0.2225 |
0.2052 |
|
|
5/16 |
18 |
2A |
0.3113 |
0.3026 |
0.2752 |
0.2712 |
0.2431 |
|
24 |
2A |
0.3114 |
0.3042 |
0.2843 |
0.2806 |
0.2603 |
|
|
3/8 |
16 |
2A |
0.3737 |
0.3643 |
0.3331 |
0.3287 |
0.2970 |
|
24 |
2A |
0.3739 |
0.3667 |
0.3468 |
0.3430 |
0.3228 |
|
|
7/16 |
14 |
2A |
0.4361 |
0.4258 |
0.3897 |
0.3850 |
0.3485 |
|
20 |
2A |
0.4362 |
0.4281 |
0.4237 |
0.3995 |
0.3749 |
|
|
1/2 |
13 |
2A |
0.4985 |
0.4876 |
0.4485 |
0.4435 |
0.4041 |
|
20 |
2A |
0.4987 |
0.4906 |
0.4662 |
0.4619 |
0.4374 |
|
|
9/16 |
12 |
2A |
0.5609 |
0.5495 |
0.5068 |
0.5016 |
0.4587 |
|
18 |
2A |
0.5611 |
0.5524 |
0.5250 |
0.5205 |
0.4929 |
|
|
5/8 |
11 |
2A |
0.6234 |
0.6113 |
0.5644 |
0.5589 |
0.5119 |
|
18 |
2A |
0.6236 |
0.6149 |
0.5875 |
0.5828 |
0.5449 |
|
|
3/4 |
10 |
2A |
0.7482 |
0.7353 |
0.6832 |
0.6773 |
0.6255 |
|
16 |
2A |
0.7485 |
0.7391 |
0.7079 |
0.7029 |
0.6718 |
|
|
7/8 |
9 |
2A |
0.8731 |
0.8592 |
0.8009 |
0.7946 |
0.7368 |
|
14 |
2A |
0.8734 |
0.8631 |
0.8270 |
0.8216 |
0.7858 |
|
|
1 |
8 |
2A |
0.9980 |
0.9830 |
0.9168 |
0.9100 |
0.8446 |
|
12 |
2A |
0.9982 |
0.9868 |
0.9441 |
0.9382 |
0.8960 |
|
Contact Oster Today for All Your Bolt Threading Needs
Oster is a leading expert in the bolt threading industry. With exceptional threading machines, knowledgeable experts, and exemplary customer service, we are your trusted partner for all bolt threading needs.
Contact Oster for more information, or request a quote today to get started.
