Unified Special Threads (UNS)
| BASIC DIMENSIONS AND PITCH | |||
|---|---|---|---|
| UNS designation | Basic major diameter (in) | Pitch (in) | TPI |
| 1/4-27 UNS | 0.2500 | 0.03704 | 27 |
| 5/16-27 UNS | 0.3125 | 0.03704 | 27 |
| 3/8-27 UNS | 0.3750 | 0.03704 | 27 |
| 7/16-27 UNS | 0.4375 | 0.03704 | 27 |
| 1/2-27 UNS | 0.5000 | 0.03704 | 27 |
| 9/16-27 UNS | 0.5625 | 0.03704 | 27 |
| 5/8-27 UNS | 0.6250 | 0.03704 | 27 |
| 3/4-27 UNS | 0.7500 | 0.03704 | 27 |
| 7/8-27 UNS | 0.8750 | 0.03704 | 27 |
| 1-27 UNS | 1.0000 | 0.03704 | 27 |
| 1 1/8-27 UNS | 1.1250 | 0.03704 | 27 |
The rows show the legacy 27-TPI thin-wall-tubing UNS series. UNS is also used for specified special diameter/pitch combinations; those callouts are not one universal size series.