Thread geometry - British Standard Fine (BSF)
All dimensions in inches unless otherwise stated.
 |
d1 - Minor thread diameter male d2 - Minor thread diameter female d3 - Pitch diameter d4 - Major diameter |
|---|
| Thread | Major diameter | Thread per inch | Pitch diameter | Minor diameter male thread |
|---|---|---|---|---|
| 3/16 | 0.1875 | 32 | 0.1675 | 0.1475 |
| 7/32 | 0.2187 | 28 | 0.1959 | 0.1730 |
| 1/4 | 0.2500 | 26 | 0.2254 | 0.2008 |
| 9/32 | 0.2812 | 26 | 0.2566 | 0.2320 |
| 5/16 | 0.3125 | 22 | 0.2834 | 0.2543 |
| 3/8 | 0.3750 | 20 | 0.3430 | 0.3110 |
| 7/16 | 0.4375 | 18 | 0.4019 | 0.3663 |
| 1/2 | 0.5000 | 16 | 0.4600 | 0.4200 |
| 9/16 | 0.5625 | 16 | 0.5225 | 0.4825 |
| 5/8 | 0.6250 | 14 | 0.5792 | 0.5334 |
| Thread | Major diameter | Thread per inch | Pitch diameter | Minor diameter male thread |
|---|---|---|---|---|
| 11/16 | 0.6875 | 14 | 0.6417 | 0.5959 |
| 3/4 | 0.7500 | 12 | 0.6966 | 0.6431 |
| 13/16 | 0.8125 | 12 | 0.7591 | 0.7057 |
| 7/8 | 0.8750 | 11 | 0.8168 | 0.7586 |
| 1 | 1.0000 | 10 | 0.9360 | 0.8720 |
| 1 1/8 | 1.1250 | 9 | 1.0539 | 0.9828 |
| 1 1/4 | 1.2500 | 9 | 1.1789 | 1.1078 |
| 1 3/8 | 1.3750 | 8 | 1.2950 | 1.2150 |
| 1 1/2 | 1.5000 | 8 | 1.4200 | 1.3400 |
| 1 5/8 | 1.6250 | 8 | 1.5450 | 1.4650 |
| Thread | Major diameter | Thread per inch | Pitch diameter | Minor diameter male thread |
|---|---|---|---|---|
| 1 3/4 | 1.7500 | 7 | 1.6585 | 1.5670 |
| 2 | 2.0000 | 7 | 1.9085 | 1.8170 |
| 2 1/4 | 2.2500 | 6 | 2.1433 | 2.0366 |
| 2 1/2 | 2.5000 | 6 | 2.3933 | 2.2866 |
| 2 3/4 | 2.7500 | 6 | 2.6433 | 2.5366 |
| 3 | 3.0000 | 5 | 2.8719 | 2.7438 |
| 3 1/4 | 3.2500 | 5 | 3.1219 | 2.9938 |
| 3 1/2 | 3.5000 | 4 1/2 | 3.3577 | 3.2154 |
| 3 3/4 | 3.7500 | 4 1/2 | 3.6077 | 3.4654 |
| 4 | 4.0000 | 4 1/2 | 3.8577 | 3.7154 |
| 4 1/4 | 4.2500 | 4 | 4.0900 | 3.9300 |