Normal Engagement Length of NPT Thread in Inches (A) *
* Dimensions given do not allow for variations in tapping or threading.
| Thread Size | "A" |
| 1/8" | 1/4" |
| 1/4" | 3/8" |
| 3/8" | 3/8" |
| 1/2" | 1/2" |
| 3/4" | 9/16" |
| 1" | 11/16" |
| 1-1/4" | 11/16" |
| 1-1/2" | 11/16" |
| 2" | 3/4" |
| Thread Size | "A" |
| 2-1/2" | 15/16" |
| 3" | 1" |
| 4" | 1-1/8" |
| 5" | 1-1/4" |
| 6" | 1-5/16" |
| 8" | 1-7/16" |
| 10" | 1-5/8" |
| 12" | 1-3/4" |