British Standard Whitworth Screw Threads
Course Thread Series (BSW) Table - Imperial Units
| Nominal Size | Full Diameter (inch) | Threads per Inch | Pitch (inch) | Core Diameter (inch) |
|---|---|---|---|---|
| 1/4 inch | 0.25 | 20 | 0.05 | 0.186 |
| 5/16 inch | 0.3125 | 18 | 0.0556 | 0.2414 |
| 3/8 inch | 0.375 | 16 | 0.0625 | 0.295 |
| 7/16 inch | 0.4375 | 14 | 0.0714 | 0.3461 |
| 1/2 inch | 0.5 | 12 | 0.0833 | 0.3932 |
| 9/16 inch | 0.5625 | 12 | 0.0833 | 0.4557 |
| 5/8 inch | 0.625 | 11 | 0.0909 | 0.5086 |
| 11/16 inch | 0.6875 | 11 | 0.0909 | 0.5711 |
| 3/4 inch | 0.75 | 10 | 0.1 | 0.622 |
| 13/16 inch | 0.8125 | 10 | 0.1 | 0.6845 |
| 7/8 inch | 0.875 | 9 | 0.1111 | 0.7328 |
| 15/16 inch | 0.9375 | 9 | 0.1111 | 0.7953 |
| 1 inch | 1 | 8 | 0.125 | 0.84 |
| 1 1/8 inch | 1.125 | 7 | 0.1429 | 0.942 |
| 1 1/4 inch | 1.25 | 7 | 0.1429 | 1.067 |
| 1 3/8 inch | 1.375 | 6 | 0.1667 | 1.162 |
| 1 1/2 inch | 1.5 | 6 | 0.1667 | 1.287 |
| 1 5/8 inch | 1.625 | 5 | 0.2 | 1.369 |
| 1 3/4 inch | 1.75 | 5 | 0.2 | 1.494 |
| 1 7/8 inch | 1.875 | 4.5 | 0.2222 | 1.591 |
| 2 inch | 2 | 4.5 | 0.2222 | 1.715 |
| 2 1/4 inch | 2.25 | 4 | 0.25 | 1.929 |
| 2 1/2 inch | 2.5 | 4 | 0.25 | 2.179 |
| 2 3/4 inch | 2.75 | 3.5 | 0.2857 | 2.385 |
| 3 inch | 3 | 3.5 | 0.2857 | 2.634 |
| 3 1/4 inch | 3.25 | 3.25 | 0.3077 | 2.856 |
| 3 1/2 inch | 3.5 | 3.25 | 0.3077 | 3.106 |
| 3 3/4 inch | 3.75 | 3 | 0.3333 | 3.323 |
| 4 inch | 4 | 3 | 0.3333 | 3.573 |
| 4 1/2 inch | 4.5 | 2.875 | 0.3478 | 4.055 |
| 5 inch | 5 | 2.75 | 0.3636 | 4.535 |
| 5 1/2 inch | 5.5 | 2.625 | 0.381 | 5.012 |
| 6 inch | 6 | 2.5 | 0.4 | 5.488 |
Course Thread Series (BSW) Table - Metric Units
| Nominal Size | Full Diameter (mm) | Pitch (mm) | Core Diameter (mm) |
|---|---|---|---|
| 1/4 inch | 6.35 | 1.27 | 4.72 |
| 5/16 inch | 7.94 | 1.41 | 6.13 |
| 3/8 inch | 9.52 | 1.59 | 7.49 |
| 7/16 inch | 11.11 | 1.81 | 8.79 |
| 1/2 inch | 12.70 | 2.12 | 9.99 |
| 9/16 inch | 14.29 | 2.12 | 11.57 |
| 5/8 inch | 15.88 | 2.31 | 12.92 |
| 11/16 inch | 17.46 | 2.31 | 14.51 |
| 3/4 inch | 19.05 | 2.54 | 15.80 |
| 13/16 inch | 20.64 | 2.54 | 17.39 |
| 7/8 inch | 22.22 | 2.82 | 18.61 |
| 15/16 inch | 23.81 | 2.82 | 20.20 |
| 1 inch | 25.40 | 3.17 | 21.34 |
| 1 1/8 inch | 28.57 | 3.63 | 23.93 |
| 1 1/4 inch | 31.75 | 3.63 | 27.10 |
| 1 3/8 inch | 34.92 | 4.23 | 29.51 |
| 1 1/2 inch | 38.10 | 4.23 | 32.69 |
| 1 5/8 inch | 41.27 | 5.08 | 34.77 |
| 1 3/4 inch | 44.45 | 5.08 | 37.95 |
| 1 7/8 inch | 47.63 | 5.64 | 40.41 |
| 2 inch | 50.80 | 5.64 | 43.56 |
| 2 1/4 inch | 57.15 | 6.35 | 49.00 |
| 2 1/2 inch | 63.50 | 6.35 | 55.35 |
| 2 3/4 inch | 69.85 | 7.26 | 60.58 |
| 3 inch | 76.20 | 7.26 | 66.90 |
| 3 1/4 inch | 82.55 | 7.82 | 72.54 |
| 3 1/2 inch | 88.90 | 7.82 | 78.89 |
| 3 3/4 inch | 95.25 | 8.47 | 84.40 |
| 4 inch | 101.60 | 8.47 | 90.75 |
| 4 1/2 inch | 114.30 | 8.83 | 103.00 |
| 5 inch | 127.00 | 9.24 | 115.19 |
| 5 1/2 inch | 139.70 | 9.68 | 127.30 |
| 6 inch | 152.40 | 10.16 | 139.40 |
Inspiration and Source for Table
Book: Folwers Mechanics' and Machinists' Pocket-Book. 1961 (Fifty Third Anunual Edition) - Scientific Publishing Company
All data is approximate and for general information only. Data has been cross-refrenced with various sources to ensure accuracy but errors may still exist.
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