BS 4190 Standard
Dimensions of ISO metric hexagon head bolts and screws faced under head or faced under head and turned on shank
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Nominal size and thread diameter d |
Pitch of thread (coarse pitch series) |
Diameter of unthreaded shank d |
Width across flats s |
Width across corners e |
Height of head K |
Radius under head R |
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| Faced under head | Faced under head and turned on shank | ||||||||||||
| max. | min. | max. | min. | max. | min. | max. | min. | max. | min. | max. | min. | ||
| M6 | 1 | 6.48 | 5.52 | 6.00 | 5.82 | 10.00 | 9.64 | 11.5 | 10.89 | 4.24 | 3.76 | 0.4 | 0.25 |
| M8 | 1.25 | 8.58 | 7.42 | 8.00 | 7.78 | 13.00 | 12.57 | 15.0 | 14.20 | 5.74 | 5.26 | 0.8 | 0.4 |
| M10 | 1.5 | 10.58 | 9.42 | 10.00 | 9.78 | 17.00 | 16.57 | 19.6 | 18.72 | 7.29 | 6.71 | 0.8 | 0.4 |
| M12 | 1.75 | 12.70 | 11.30 | 12.00 | 11.73 | 19.00 | 18.48 | 21.9 | 20.88 | 8.29 | 7.71 | 1.25 | 0.6 |
| M16 | 2 | 16.70 | 15.30 | 16.00 | 15.73 | 24.00 | 23.16 | 27.7 | 26.17 | 10.29 | 9.71 | 1.25 | 0.6 |
| M20 | 2.5 | 20.84 | 19.16 | 20.00 | 19.67 | 30.00 | 29.16 | 34.6 | 32.95 | 13.35 | 12.65 | 1.78 | 0.8 |
| (M22) | 2.5 | 22.84 | 21.16 | 22.00 | 21.67 | 32.00 | 31.00 | 36.9 | 35.03 | 14.35 | 13.65 | 1.78 | 0.8 |
| M24 | 3 | 24.84 | 23.16 | 24.00 | 23.67 | 36.00 | 35.00 | 41.6 | 39.55 | 15.35 | 14.65 | 1.78 | 0.8 |
| (M27) | 3 | 27.84 | 26.16 | 27.00 | 26.67 | 41.00 | 40.00 | 47.3 | 45.20 | 17.35 | 16.65 | 2.28 | 1.0 |
| M30 | 3.5 | 30.84 | 29.16 | 30.00 | 29.67 | 46.00 | 45.00 | 53.1 | 50.85 | 19.42 | 18.58 | 2.28 | 1.0 |
| (M33) | 3.5 | 34.00 | 32.00 | 33.00 | 32.61 | 50.00 | 49.00 | 57.7 | 55.37 | 21.42 | 20.58 | 2.28 | 1.0 |
| M36 | 4 | 37.00 | 35.00 | 36.00 | 35.61 | 55.00 | 53.80 | 63.5 | 60.79 | 23.42 | 22.58 | 2.7 | 1.0 |
| (M39) | 4 | 40.00 | 38.00 | 39.00 | 38.61 | 60.00 | 58.80 | 69.3 | 66.44 | 25.42 | 24.58 | 2.7 | 1.0 |
| M42 | 4.5 | 43.00 | 41.00 | 42.00 | 41.61 | 65.00 | 63.80 | 75.1 | 72.09 | 26.42 | 25.58 | 2.8 | 1.2 |
| (M45) | 4.5 | 46.00 | 44.00 | 45.00 | 44.61 | 70.00 | 68.80 | 80.8 | 77.74 | 28.42 | 27.58 | 3.3 | 1.2 |
| M48 | 5.0 | 49.00 | 47.00 | 48.00 | 47.61 | 75.00 | 73.80 | 86.6 | 83.39 | 30.42 | 29.58 | 3.8 | 1.6 |
| (M52) | 5.0 | 53.20 | 50.80 | 52.00 | 51.54 | 80.00 | 78.80 | 92.4 | 89.04 | 33.50 | 32.50 | 4.7 | 1.6 |
| M56 | 5.5 | 57.20 | 54.80 | 56.00 | 55.54 | 85.00 | 83.00 | 98.1 | 94.47 | 35.50 | 34.50 | 4.9 | 2.0 |
| (M60) | 5.5 | 61.20 | 58.80 | 60.00 | 59.54 | 90.00 | 88.60 | 103.9 | 100.12 | 38.50 | 37.50 | 4.9 | 2.0 |
| M64 | 6 | 65.20 | 62.80 | 64.00 | 63.54 | 95.00 | 93.60 | 109.7 | 105.77 | 40.50 | 39.50 | 4.9 | 2.0 |
| (M68) | 6 | 69.20 | 66.80 | 68.00 | 67.54 | 100.00 | 98.60 | 115.5 | 111.42 | 43.50 | 42.50 | 4.9 | 2.0 |
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NOTE: Sizes in brackets are non-preferred. |
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