Australian Bolt Torque Chart — AS 4100 M12-M36
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Complete reference for bolt torque-tension relationships per AS 4100:2020 for Australian structural bolting. Grade 8.8 and 10.9 bolts M12 to M36, minimum pretension per Clause 9.3.8.3.
Minimum Bolt Pretension
Pd = 0.70 × fuf × At
| Size | At (mm²) | Gr 8.8 (kN) | Gr 10.9 (kN) |
|---|---|---|---|
| M12 | 84.3 | 49.0 | 61.4 |
| M16 | 157 | 91.2 | 114.3 |
| M20 | 245 | 142.3 | 178.4 |
| M22 | 303 | 176.0 | 220.6 |
| M24 | 353 | 205.1 | 257.0 |
| M27 | 459 | 266.7 | 334.2 |
| M30 | 561 | 326.0 | 408.4 |
| M36 | 817 | 474.7 | 594.8 |
Installation Torque — T = K × D × P
| Size | Pd (kN) | K=0.33 (Nm) | K=0.25 (Nm) | K=0.20 (Nm) |
|---|---|---|---|---|
| M16 | 91.2 | 481 | 365 | 292 |
| M20 | 142.3 | 939 | 712 | 569 |
| M24 | 205.1 | 1624 | 1231 | 984 |
| M30 | 326.0 | 3227 | 2445 | 1956 |
| M36 | 474.7 | 5640 | 4273 | 3418 |
Tightening Methods
| Method | Accuracy | Clause | Use |
|---|---|---|---|
| Torque control (calibrated) | ±15% | 9.3.8.4 | Small projects |
| Direct tension indicator | ±10% | 9.3.8.5 | General structural |
| Turn-of-nut | ±10% | 9.3.8.6 | Large connections |
| Hydraulic tensioner | ±5% | 9.3.8.7 | Critical connections |
Design Resources
- [[Australian Steel Grades|/reference/australian-steel-grades/]] | [[Australian Steel Properties|/reference/australian-steel-properties/]] | [[Australian Beam Sizes|/reference/au-beam-sizes/]] | [[Australian Bolt Capacity|/reference/australian-bolt-capacity/]] | [[AS 4100 Beam Design|/reference/as4100-beam-design-example/]] | [[All Australian References|/reference/]]
FAQ
Installation torque for M20 Grade 8.8? 939 Nm (K=0.33). With lubrication (K=0.20): 569 Nm.
Can turn-of-nut replace torque control? Yes, per Clause 9.3.8. 1/2 turn for bolts ≤4d, 2/3 turn for longer from snug-tight.
Torque for M16 Grade 8.8? Pd=91.2 kN. K=0.33 → 481 Nm. K=0.20 → 292 Nm.
Educational Use Only — This reference is for educational and preliminary design purposes only. All structural designs must be independently verified by a licensed Professional Engineer (PE) or Structural Engineer (SE) in accordance with AS 4100:2020 and all applicable Australian Standards. Results are not for construction.