M22 bolt torque
An M22 x 2.5 bolt takes 600 N·m in class 8.8, 830 in 10.9 and 970 in 12.9, dry, at 75% of proof load (442, 612 and 715 ft-lb). Fine pitches take a little more. Oiled threads take a quarter less.
Sources checked
| Thread | Class | DryK 0.20 | Zinc platedK 0.20 | OiledK 0.15 | WaxedK 0.10 | Clamp load |
|---|---|---|---|---|---|---|
| M22 x 2.5coarse | Class 4.6 | 166225 | 166225 | 124169 | 83.0112 | 11,495 lbf51.1 kN |
| Class 8.8 | 442600 | 442600 | 332450 | 221300 | 30,653 lbf136.3 kN | |
| Class 10.9 | 612830 | 612830 | 459622 | 306415 | 42,403 lbf188.6 kN | |
| Class 12.9 | 715970 | 715970 | 537727 | 358485 | 49,555 lbf220.4 kN | |
| M22 x 1.5fine | Class 4.6 | 182247 | 182247 | 137185 | 91.2124 | 12,633 lbf56.2 kN |
| Class 8.8 | 486659 | 486659 | 365495 | 243330 | 33,688 lbf149.8 kN | |
| Class 10.9 | 673912 | 673912 | 505684 | 336456 | 46,601 lbf207.3 kN | |
| Class 12.9 | 7861,066 | 7861,066 | 590799 | 393533 | 54,462 lbf242.3 kN |
Work out M22 torque
Change grade, threads or preload
M22 x 2.5 Class 8.8, dry, plain steel
442ft-lb600N·m
- Clamp load
- 30,653 lbf (136.3 kN)
- Proof load
- 181.8 kN
The working
- Tensile stress area. A = π/4 × (d − 0.9382 × P)² = π/4 × (22 − 0.9382 × 2.5)² = 303 mm²
- Proof load. Class 8.8 proof stress is 600 MPa, so A × stress = 181,800 N.
- Clamp load. 75% of proof load = 136,350 N.
- Torque. T = K × D × F = 0.2 × 22 mm × 136.35 kN = 600 N·m (442 ft-lb).
Where the M22 x 2.5 numbers come from
The M22 x 2.5 coarse thread has a tensile stress area of 303 mm². A Class 10.9 bolt’s proof stress is 830 MPa, so its proof load is 251,490 N, and 75% of that is a clamp load of 188,618 N.
Torque = K × D × F = 0.20 × 22 mm × 188.62 kN = 830 N·m (612 ft-lb) dry. With oil (K 0.15) it’s 622 N·m (459 ft-lb).
Other sizes
All sizes on one page: the metric bolt torque chart.
Questions
What torque for an M22 x 2.5 Class 10.9 bolt?
830 N·m (612 ft-lb) dry and 622 N·m (459 ft-lb) oiled, at 75% of proof load. That clamps the joint with 42,403 lbf (188.6 kN).
What torque for an M22 x 2.5 Class 8.8 bolt?
600 N·m (442 ft-lb) dry, at 75% of proof load; a quarter less with oiled threads.
Coarse or fine thread?
Use whichever the bolt has. The fine M22 x 1.5 thread has a bigger stress area than the coarse one, so it takes slightly more torque for the same clamp. A thread gauge settles it.
Does this apply to wheel nuts or engine bolts?
No. Use the vehicle maker’s value for those: see lug nut torque by vehicle. These numbers are for general-purpose steel bolts where no spec exists.
Sources
- Fastenal: Mechanical properties per ISO 898-1 (externally threaded fasteners): proof stress by property class (checked October 14, 2026)
- Engineering Toolbox: Metric bolts: minimum ultimate tensile and proof loads, with ISO 898-1 stress areas (checked October 14, 2026)
- Engineering Toolbox: ISO 724 metric threads: coarse and fine pitches with tensile stress areas (checked October 14, 2026)
- Engineering Toolbox: Threaded bolts: tensile stress area formulas for unified and ISO metric threads (checked October 14, 2026)
- Fastenal: Torque–tension relationship for metric fasteners, property classes 4.6, 8.8, 10.9 and 12.9 (checked October 14, 2026)
- Portland Bolt: Bolt torque chart: T = KDP at 75% of proof load, with K for plain, waxed and galvanized bolts (checked October 14, 2026)
Spotted a number that doesn’t match your manual or a source? Tell us; corrections are logged on the sources page.