International Measuring and Identification Guide - BSPP (British Standard Pipe Parallel) - BS 2779
| Male Tapered O.D | Female Tapered I.D. | |||
| Thread Size | MM | Frac. | MM | Frac. |
| 1/8 - 28 | 9.5 | 3/8 | 8.7 | 11/32 |
| 1/4 - 19 | 13.5 | 17/32 | 11.9 | 15/32 |
| 3/8 - 19 | 16.7 | 21/32 | 15.1 | 19/32 |
| 1/2 - 14 | 20.6 | 13/16 | 19.1 | 3/4 |
| 5/8 - 14 | 23.0 | 29/32 | 20.6 | 13/16 |
| 3/4 - 14 | 26.2 | 1 1/32 | 23.0 | 29/32 |
| 1 - 11 | 33.3 | 1 5/16 | 30.9 | 1 7/32 |
| 1 1/4 - 11 | 42.1 | 1 21/32 | 34.9 | 1 3/8 |
| 1 1/2 - 11 | 47.6 | 1 7/8 | 45.2 | 1 25/32 |
| 2 - 11 | 59.5 | 2 11/32 | 57.2 | 2 1/4 |
| The threads retain the connection. | ||||
| Note: The BSPP is similar to NPSM connectors but not interchangeable. | ||||