M14 bolt torque
An M14 x 2 bolt takes 140 N·m in class 8.8, 200 in 10.9 and 234 in 12.9, dry, at 75% of proof load (103, 148 and 173 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 |
|---|---|---|---|---|---|---|
| M14 x 2coarse | Class 4.6 | 40.154.3 | 40.154.3 | 30.140.8 | 20.027.2 | 4,363 lbf19.4 kN |
| Class 8.8 | 103140 | 103140 | 77.5105 | 51.770.0 | 11,246 lbf50.0 kN | |
| Class 10.9 | 148200 | 148200 | 111150 | 73.9100 | 16,094 lbf71.6 kN | |
| Class 12.9 | 173234 | 173234 | 130176 | 86.4117 | 18,808 lbf83.7 kN | |
| M14 x 1.5fine | Class 4.6 | 43.659.1 | 43.659.1 | 32.744.3 | 21.829.5 | 4,742 lbf21.1 kN |
| Class 8.8 | 112152 | 112152 | 84.2114 | 56.176.1 | 12,224 lbf54.4 kN | |
| Class 10.9 | 161218 | 161218 | 121163 | 80.3109 | 17,493 lbf77.8 kN | |
| Class 12.9 | 188255 | 188255 | 141191 | 93.9127 | 20,444 lbf90.9 kN |
Work out M14 torque
Change grade, threads or preload
M14 x 2 Class 8.8, dry, plain steel
103ft-lb140N·m
- Clamp load
- 11,246 lbf (50.0 kN)
- Proof load
- 66.7 kN
The working
- Tensile stress area. A = π/4 × (d − 0.9382 × P)² = π/4 × (14 − 0.9382 × 2)² = 115 mm²
- Proof load. Class 8.8 proof stress is 580 MPa, so A × stress = 66,700 N.
- Clamp load. 75% of proof load = 50,025 N.
- Torque. T = K × D × F = 0.2 × 14 mm × 50.02 kN = 140 N·m (103 ft-lb).
Where the M14 x 2 numbers come from
The M14 x 2 coarse thread has a tensile stress area of 115 mm². A Class 10.9 bolt’s proof stress is 830 MPa, so its proof load is 95,450 N, and 75% of that is a clamp load of 71,588 N.
Torque = K × D × F = 0.20 × 14 mm × 71.59 kN = 200 N·m (148 ft-lb) dry. With oil (K 0.15) it’s 150 N·m (111 ft-lb).
Other sizes
All sizes on one page: the metric bolt torque chart.
Questions
What torque for an M14 x 2 Class 10.9 bolt?
200 N·m (148 ft-lb) dry and 150 N·m (111 ft-lb) oiled, at 75% of proof load. That clamps the joint with 16,094 lbf (71.6 kN).
What torque for an M14 x 2 Class 8.8 bolt?
140 N·m (103 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 M14 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.