Whitworth & British
BSF British Standard Fine
British threads based on Whitworth's 55° profile with rounded crests and roots, still found on older machinery, pipe fittings and model engineering.
- Standard
- BS 84
- Flank angle
- 55°
- Sizes listed
- 30
- Range
- BSF 3/16" – BSF 4 1/4"
| Nominal Diameter | Major Diameter Inch | Major Diameter mm | Tapping Drill Size mm | TPI | Pitch mm |
|---|---|---|---|---|---|
| BSF 3/16" | 0.1875 | 4.763 | 3.950 | 32 | 0.794 |
| BSF 7/32" | 0.2188 | 5.556 | 4.600 | 28 | 0.907 |
| BSF 1/4" | 0.2500 | 6.350 | 5.300 | 26 | 0.977 |
| BSF 9/32" | 0.2812 | 7.144 | 6.100 | 26 | 0.977 |
| BSF 5/16" | 0.3125 | 7.938 | 6.750 | 22 | 1.154 |
| BSF 3/8" | 0.3750 | 9.525 | 8.200 | 20 | 1.270 |
| BSF 7/16" | 0.4375 | 11.113 | 9.580 | 18 | 1.411 |
| BSF 1/2" | 0.5000 | 12.700 | 11.100 | 16 | 1.587 |
| BSF 9/16" | 0.5625 | 14.288 | 12.600 | 16 | 1.587 |
| BSF 5/8" | 0.6250 | 15.875 | 13.900 | 14 | 1.814 |
| BSF 11/16" | 0.6875 | 17.463 | 15.500 | 14 | 1.814 |
| BSF 3/4" | 0.7500 | 19.050 | 16.700 | 12 | 2.117 |
| BSF 7/8" | 0.8750 | 22.225 | 19.600 | 11 | 2.309 |
| BSF 1" | 1.0000 | 25.400 | 22.500 | 10 | 2.540 |
| BSF 1 1/8" | 1.1250 | 28.575 | 25.400 | 9 | 2.822 |
| BSF 1 1/4" | 1.2500 | 31.750 | 28.560 | 9 | 2.822 |
| BSF 1 3/8" | 1.3750 | 34.925 | 31.350 | 8 | 3.175 |
| BSF 1 1/2" | 1.5000 | 38.100 | 34.500 | 8 | 3.175 |
| BSF 1 5/8" | 1.6250 | 41.275 | 37.710 | 8 | 3.175 |
| BSF 1 3/4" | 1.7500 | 44.450 | 40.480 | 7 | 3.628 |
| BSF 2" | 2.0000 | 50.800 | 46.830 | 7 | 3.628 |
| BSF 2 1/4" | 2.2500 | 57.150 | 52.400 | 6 | 4.233 |
| BSF 2 1/2" | 2.5000 | 63.500 | 58.740 | 6 | 4.233 |
| BSF 2 3/4" | 2.7500 | 69.850 | 65.000 | 6 | 4.233 |
| BSF 3" | 3.0000 | 76.200 | 70.500 | 5 | 5.080 |
| BSF 3 1/4" | 3.2500 | 82.550 | 79.370 | 5 | 5.080 |
| BSF 3 1/2" | 3.5000 | 88.900 | 82.550 | 4.5 | 5.644 |
| BSF 3 3/4" | 3.7500 | 95.250 | 88.900 | 4.5 | 5.644 |
| BSF 4" | 4.0000 | 101.600 | 95.250 | 4.5 | 5.644 |
| BSF 4 1/4" | 4.2500 | 107.950 | 101.600 | 4 | 6.350 |
Reference values only. Verify against the current edition of the governing standard before use in production drawings or manufacturing. Provided by Micro Components as a free engineering resource.