Whitworth's Standard Threads for Pipes (in)
| Nominal
Bore of Pipe | Diameter
of Pipe | Diameter
at Bottom of Thread | Number
of Threads per Inch |
|---|---|---|---|
| 1/8 | 0.382 | 0.336 | 28 |
| 1/4 | 0.518 | 0.451 | 19 |
| 3/8 | 0.656 | 0.589 | 19 |
| 1/2 | 0.826 | 0.734 | 14 |
| 5/8 | 0.902 | 0.811 | 14 |
| 3/4 | 1.04 | 0.949 | 14 |
| 7/8 | 1.189 | 1.097 | 14 |
| 1 | 1.309 | 1.192 | 11 |
| 1 1/8 | 1.492 | 1.375 | 11 |
| 1 1/4 | 1.65 | 1.533 | 11 |
| 1 3/8 | 1.745 | 1.628 | 11 |
| 1 1/2 | 1.882 | 1.765 | 11 |
| 1 5/8 | 2.022 | 1.965 | 11 |
| 1 3/4 | 2.16 | 2.042 | 11 |
| 1 7/8 | 2.245 | 2.128 | 11 |
| 2 | 2.347 | 2.23 | 11 |
| 2 1/8 | 2.467 | 2.351 | 11 |
| 2 1/4 | 2.587 | 2.47 | 11 |
| 2 3/8 | 2.794 | 2.678 | 11 |
| 2 1/2 | 3 | 2.882 | 11 |
| 2 5/8 | 3.124 | 3.009 | 11 |
| 2 3/4 | 3.247 | 3.13 | 11 |
| 2 7/8 | 3.367 | 3.251 | 11 |
| 3 | 3.485 | 3.368 | 11 |
| 3 1/4 | 3.698 | 3.581 | 11 |
| 3 1/2 | 3.912 | 3.795 | 11 |
| 3 3/4 | 4.125 | 4.008 | 11 |
| 4 | 4.340 | 4.223 | 11 |