The BSW is the Coarse Thread series of British Standard 84:1956 - Parallel Screw Threads of Whitworth Form. The dimensions given in the tables on the following pages for the major, effective, and minor diameters are, respec- tively, the maximum limits of these diameters for bolts and the minimum limits for nuts.
| Nominal Size Ww | Thread Form Type | Major Diameter mm d=D | Pitch mm p | Threads per inch tpi | Pitch Diameter mm d2=D2 | Minor Diameter Male Thd. d3 | Thread Height H1 | Tap Drill Diameter mm |
|---|---|---|---|---|---|---|---|---|
| 1/16" | BSW | 1.587 | 0.423 | 60 | 1.315 | 1.05 | 0.27 | 1.15 |
| 3/32" | BSW | 2.381 | 0.529 | 48 | 2.041 | 1.703 | 0.338 | 1.9 |
| 1/8" | BSW | 3.175 | 0.635 | 40 | 2.768 | 2.362 | 0.406 | 2.5 |
| 5/32" | BSW | 3.969 | 0.793 | 32 | 3.459 | 2.952 | 0.507 | 3.2 |
| 3/16" | BSW | 4.762 | 1.058 | 24 | 4.084 | 3.407 | 0.677 | 3.7 |
| 7/32 | BSW | 5.556 | 1.058 | 24 | 4.878 | 4.201 | 0.677 | 4.5 |
| 1/4" | BSW | 6.35 | 1.27 | 20 | 5.537 | 4.724 | 0.813 | 5.1 |
| 5/16 | BSW | 7.938 | 1.411 | 18 | 7.034 | 6.131 | 0.904 | 6.5 |
| 3/8" | BSW | 9.525 | 1.588 | 16 | 8.509 | 7.492 | 1.017 | 7.9 |
| 7/16 | BSW | 11.113 | 1.814 | 14 | 9.951 | 8.789 | 1.162 | 9.2 |
| 1/2" | BSW | 12.7 | 2.117 | 12 | 11.345 | 9.99 | 1.355 | 10.4 |
| 9/16" | BSW | 14.29 | 2.117 | 12 | 12.93 | 11.58 | 1.355 | 11.89 |
| 5/8" | BSW | 15.876 | 2.309 | 11 | 14.397 | 12.918 | 1.479 | 13.4 |
| 3/4" | BSW | 19.051 | 2.54 | 10 | 17.424 | 15.798 | 1.627 | 16.25 |
| 7/8" | BSW | 22.226 | 2.822 | 9 | 20.419 | 18.611 | 1.807 | 19.25 |
| 1" | BSW | 25.4 | 3.175 | 8 | 23.368 | 21.335 | 2.033 | 22 |
| 1 1/8" | BSW | 28.576 | 3.629 | 7 | 26.253 | 23.929 | 2.324 | 24.5 |
| 1 1/4" | BSW | 31.751 | 3.629 | 7 | 29.428 | 27.104 | 2.324 | 27.25 |
| 1 3/8" | BSW | 34.926 | 4.233 | 6 | 32.215 | 29.505 | 2.711 | 30.25 |
| 1 1/2" | BSW | 38.1 | 4.233 | 6 | 35.391 | 32.68 | 2.711 | 33.5 |
| 1 5/8" | BSW | 41.277 | 5.08 | 5 | 38.024 | 34.771 | 3.253 | 35.5 |
| 1 3/4" | BSW | 44.452 | 5.08 | 5 | 41.199 | 37.946 | 3.253 | 38.5 |
| 1 7/8" | BSW | 47.627 | 5.645 | 4 1/2 | 44.012 | 40.398 | 3.614 | 41.25 |
| 2" | BSW | 50.802 | 5.645 | 4 1/2 | 47.187 | 43.573 | 3.614 | 44.5 |
| 2 1/4" | BSW | 57.152 | 6.35 | 4 | 53.086 | 49.02 | 4.066 | 50 |
| 2 1/2" | BSW | 63.502 | 6.35 | 4 | 59.436 | 55.37 | 4.066 | 56 |
| 2 3/4" | BSW | 69.853 | 7.257 | 3 1/2 | 65.205 | 60.558 | 4.647 | 61.5 |
| 3" | BSW | 76.203 | 7.257 | 3 1/2 | 71.556 | 66.909 | 4.647 | 68 |
| 3 1/4" | BSW | 82.553 | 7.816 | 3 1/4 | 77.548 | 72.544 | 5.005 | 73.75 |
| 3 1/2" | BSW | 88.903 | 7.816 | 3 1/4 | 83.899 | 78.894 | 5.005 | 80 |
| 3 3/4" | BSW | 95.254 | 8.467 | 3 | 89.832 | 84.41 | 5.422 | 85.5 |
| 4 | BSW | 101.604 | 8.467 | 3 | 96.182 | 90.76 | 5.422 | 92 |
| 4 1/4" | BSW | 107.954 | 8.835 | 2 7/8 | 102.297 | 96.639 | 5.657 | 98 |
| 4 1/2" | BSW | 114.304 | 8.835 | 2 7/8 | 108.647 | 102.99 | 5.657 | 104.2 |
| 4 3/4" | BSW | 120.665 | 9.237 | 2 3/4 | 114.74 | 108.625 | 5.915 | 110 |
| 5" | BSW | 127.005 | 9.237 | 2 3/4 | 121.09 | 115.176 | 5.915 | 116.5 |
| 5 1/4" | BSW | 133.355 | 9.677 | 2 5/8 | 127.159 | 120.963 | 6.196 | 122.5 |
| 5 1/2" | BSW | 139.705 | 9.677 | 2 5/8 | 133.509 | 127.313 | 6.196 | 128.5 |
| 5 3/4" | BSW | 146.055 | 10.16 | 2 1/2 | 139.549 | 133.043 | 6.506 | 134.5 |
| 6" | BSW | 152.406 | 10.16 | 2 1/2 | 145.9 | 139.394 | 6.506 | 141 |