BSW British Standard Whitworth
BS thread - 55° profile
| Size | TPI | Pitch in | Ext Major in | Int Minor in | Tap Drill Size in | Tap Drill Size mm |
|---|---|---|---|---|---|---|
| 1/16" | 60 | 0.0167 | 0.0625 | 0.0411 | #56 | 1.2 |
| 3/32" | 48 | 0.0208 | 0.0938 | 0.0672 | #49 | 1.9 |
| 1/8" | 40 | 0.0250 | 0.1250 | 0.0930 | #39 | 2.6 |
| 5/32" | 32 | 0.0312 | 0.1563 | 0.1163 | #30 | 3.2 |
| 3/16" | 24 | 0.0417 | 0.1875 | 0.1341 | #26 | 3.7 |
| 7/32" | 24 | 0.0417 | 0.2188 | 0.1654 | #16 | 4.5 |
| 1/4" | 20 | 0.0500 | 0.2500 | 0.1860 | #9 | 5.1 |
| 5/16" | 18 | 0.0556 | 0.3125 | 0.2413 | F | 6.5 |
| 3/8" | 16 | 0.0625 | 0.3750 | 0.2950 | 5/16" | 7.9 |
| 7/16" | 14 | 0.0714 | 0.4375 | 0.3461 | U | 9.3 |
| 1/2" | 12 | 0.0833 | 0.5000 | 0.3933 | Z | 10.5 |
| 9/16" | 12 | 0.0833 | 0.5625 | 0.4558 | 15/32" | 12.1 |
| 5/8" | 11 | 0.0909 | 0.6250 | 0.5086 | 17/32" | 13.5 |
| 11/16" | 11 | 0.1000 | 0.6875 | 0.5594 | 19/32" | 15.0 |
| 3/4" | 10 | 0.1111 | 0.7500 | 0.6077 | 41/64" | 16.3 |
| 13/16" | 10 | 0.1250 | 0.8125 | 0.6524 | 45/64" | 18.0 |
| 7/8" | 9 | 0.1429 | 0.8750 | 0.6920 | 3/4" | 19.3 |
| 15/16" | 9 | 0.1429 | 0.9375 | 0.7545 | 13/16" | 20.8 |
| 1" | 8 | 0.1667 | 1.0000 | 0.7865 | 55/64" | 22.0 |
| 1 1/8" | 7 | 0.1667 | 1.1250 | 0.9115 | 31/32" | 24.8 |
| 1 1/4" | 7 | 0.2000 | 1.2500 | 0.9939 | 1 3/32" | 28.0 |
| 1 3/8" | 6 | 0.2000 | 1.3750 | 1.1189 | 1 3/16" | 30.2 |
| 1 1/2" | 6 | 0.2222 | 1.5000 | 1.2154 | 1 5/16" | 33.5 |
| 1 5/8" | 5 | 0.2222 | 1.6250 | 1.3404 | 1 25/64" | 35.5 |
| 1 3/4" | 5 | 0.2500 | 1.7500 | 1.4298 | 1 17/32" | 39.0 |
| 1 7/8" | 4.5 | 0.2500 | 1.8750 | 1.5548 | 1 5/8" | 41.5 |
| 2" | 4.5 | 0.2857 | 2.0000 | 1.6341 | 1 49/64" | 44.5 |
| 2 1/4" | 4 | 0.2857 | 2.2500 | 1.8841 | 1 31/32" | 51.0 |
| 2 1/2" | 4 | 0.3077 | 2.5000 | 2.1059 | 2 13/64" | 57.0 |
| 2 3/4" | 3.5 | 0.3077 | 2.7500 | 2.3559 | 2 27/64" | 61.5 |
| 3" | 3.5 | 0.3333 | 3.0000 | 2.5732 | 2 11/16" | 68.0 |
| 3 1/4" | 3.25 | 0.3333 | 3.2500 | 2.8232 | 2 29/32" | 73.5 |
| 3 1/2" | 3.25 | 0.3478 | 3.5000 | 3.0546 | 3 5/32" | 80.0 |
| 3 3/4" | 3 | 0.3478 | 3.7500 | 3.3046 | 3 3/8" | 85.5 |
| 4" | 3 | 0.3637 | 4.0000 | 3.5342 | 3 5/8" | 92.0 |
| 4 1/4" | 2.875 | 0.3637 | 4.2500 | 3.7842 | 4 55/64" | 98.0 |
| 4 1/2" | 2.875 | 0.3810 | 4.5000 | 4.0121 | 4 7/64" | 104.0 |
| 4 3/4" | 2.75 | 0.3810 | 4.7500 | 4.2621 | 4 11/32" | 110.0 |
| 5" | 2.75 | 0.4000 | 5.0000 | 4.4877 | 4 19/32" | 116.5 |
| 5 1/4" | 2.625 | 0.4000 | 5.2500 | 4.7377 | 4 53/64" | 122.5 |
| 5 1/2" | 2.625 | 0.3810 | 5.5000 | 5.0121 | 5 1/16" | 128.5 |
| 5 3/4" | 2.5 | 0.4000 | 5.7500 | 5.2377 | 5 19/64" | 134.5 |
| 6" | 2.5 | 0.4000 | 6.0000 | 5.4877 | 5 9/16" | 141.0 |