British Standard Whitworth List of thread sizes Whitworth thread sizes

| Whitworth_size_in | Core_diameter_in | Threads_per_inch | Pitch_in | Tapping_drill_size_ |
|---|---|---|---|---|
| 9/16 | 0.4558 | 12 | 0.0833 | 12.1 mm (0.4764 in) |
| 5/8 | 0.5086 | 11 | 0.0909 | 13.5 mm (0.5315 in) |
| 11/16 | 0.5711 | 11 | 0.0909 | 15 mm (0.5906 in) |
| 3/4 | 0.6219 | 10 | 0.1 | 16.27 mm (0.6406 in) |
| 13/16 | 0.6845 | 10 | 0.1 | 18 mm (0.7087 in) |
| 7/8 | 0.7327 | 9 | 0.1111 | 19.25 mm (0.7579 in) |
| 15/16 | 0.7953 | 9 | 0.1111 | 20.75 mm (0.8169 in) |
| 1 | 0.8399 | 8 | 0.125 | 22 mm (0.8661 in) |
| 1 1/8 | 0.9420 | 7 | 0.1429 |  |
| 1 1/4 | 1.0670 | 7 | 0.1429 |  |
| 1 1/2 | 1.2866 | 6 | 0.1667 |  |
| 1 3/4 | 1.4939 | 5 | 0.2 |  |
| 2 | 1.7154 | 4.5 | 0.2222 |  |
| 2 1/2 | 2.180 | 4 | 0.250 |  |