In the United States, most standard fasteners follow a predictable set of thread counts based on diameter and series, but the numbers can still be easy to mix up when you’re working across different sizes. This guide provides a clear TPI table for common US bolt dimensions so you can verify thread counts quickly and avoid mismatched parts during assembly or repair.
| Bolt Size | Coarse Thread (UNC) | Fine Thread (UNF) |
|---|---|---|
| #0000 | – | 160 |
| #000 | – | 120 |
| #00 | – | 90 |
| #0 | 80 | 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″ | 4.5 | – |
MISUMI USA carries a wide range of industrial manufacturing components – including nuts, and bolts– for your next project or machine fix. If you have any questions about measurement or sizing, feel free to connect with our product experts, and engineers. Also, if you are looking for more insights be sure to check out our other blog articles, including: Pilot Hole Sizes, Wood Screw Diameter Table, External Screw Threads Size Chart, and more.
Author: Scott Bredemann | Updated: 12/4/2025
Disclaimer:
The content on this webpage is for informational purposes only. MISUMI makes no guarantees, expressed or implied, regarding the accuracy, completeness, or validity of the information. Performance parameters, tolerances, designs, materials, or processes should not be assumed to reflect third-party suppliers’ or manufacturers’ deliverables within MISUMI’s network. Buyers are responsible for specifying their part requirements.