GB 5784 – 1986 – bu lông lục giác
| Screw Thread | M3 | M4 | M5 | M6 | M8 | M10 | M12 | (M14) | M16 | M20 | |
| P ① | Pitch | 0.5 | 0.7 | 0.8 | 1 | 1.25 | 1.5 | 1.75 | 2 | 2 | 2.5 |
| b | L≤125 | 12 | 14 | 16 | 18 | 22 | 26 | 30 | 34 | 38 | 46 |
| 125＜L≤200 | – | – | – | – | 28 | 32 | 36 | 40 | 44 | 52 | |
| da | max | 3.6 | 4.7 | 5.7 | 6.8 | 9.2 | 11.2 | 13.7 | 15.7 | 17.7 | 22.4 |
| dw | min | 4.4 | 5.7 | 6.7 | 8.7 | 11.4 | 14.4 | 16.4 | 19.2 | 22 | 27.7 |
| e | min | 5.98 | 7.5 | 8.63 | 10.89 | 14.2 | 17.59 | 19.85 | 22.78 | 26.17 | 32.95 |
| k | Nominal Size | 2 | 2.8 | 3.5 | 4 | 5.3 | 6.4 | 7.5 | 8.8 | 10 | 12.5 |
| min | 1.8 | 2.6 | 3.26 | 3.76 | 5.06 | 6.11 | 7.21 | 8.51 | 9.71 | 12.15 | |
| max | 2.2 | 3 | 3.74 | 4.24 | 5.54 | 6.69 | 7.79 | 9.09 | 10.29 | 12.85 | |
| k1 | min | 1.3 | 1.8 | 2.3 | 2.6 | 3.5 | 4.3 | 5.1 | 6 | 6.8 | 8.5 |
| s | max | 5.5 | 7 | 8 | 10 | 13 | 16 | 18 | 21 | 24 | 30 |
| min | 5.2 | 6.64 | 7.64 | 9.64 | 12.57 | 15.57 | 17.57 | 20.16 | 23.16 | 29.16 | |
| x | max | 1.25 | 1.75 | 2 | 2.5 | 3.2 | 3.8 | 4.3 | 5 | 5 | 6.3 |
| Weight of per 1000 steel products(≈kg) | – | – | – | – | – | – | – | – | – | – | |
| Length of Thread b | – | – | – | – | – | – | – | – | – | – | |
