# M22 bolt torque

Tighten an M22 × 2.5 class 8.8 bolt to 601 N·m (443 ft-lb) with dry threads, or 451 N·m when lubricated. Class 10.9 takes 831 N·m and class 12.9 takes 971 N·m.

## M22 × 2.5 torque by property class

| Property class | Dry torque (K 0.20) | Lubricated (K 0.15) | Clamp load | Proof load |
|---|---|---|---|---|
| Class 8.8 | 601 N·m (443 ft-lb) | 451 N·m (332 ft-lb) | 136.5 kN | 182.0 kN |
| Class 10.9 | 831 N·m (613 ft-lb) | 623 N·m (460 ft-lb) | 188.9 kN | 251.8 kN |
| Class 12.9 | 971 N·m (716 ft-lb) | 728 N·m (537 ft-lb) | 220.7 kN | 294.3 kN |

Clamp load = 75 % of proof load. Method: T = K × F × d.

## M22 bolt data

- Thread: M22 × 2.5 coarse
- Tensile stress area: 303.4 mm²
- Wrench: 34 mm (ISO 4014/4017), 32 mm (DIN 931/933)
- Socket head cap screw hex key: 17 mm
- Tap drill: 19.5 mm
- Clearance hole (ISO 273): 23 close, 24 normal, 26 loose (mm)

## Method

Proof stress from ISO 898-1 (600 MPa for 8.8 at this size, 830 MPa for 10.9, 970 MPa for 12.9) × tensile stress area As = π/4 × (d − 0.9382 p)². Target clamp load F = 75 % of proof load. T = K × F × d with K = 0.20 dry, 0.15 lubricated.

## FAQ

**What is the torque for an M22 8.8 bolt?**
About 601 N·m (443 ft-lb) with dry threads and about 451 N·m lubricated, based on 75 % of proof load.

**What is the torque for an M22 10.9 bolt?**
About 831 N·m (613 ft-lb) dry and 623 N·m lubricated.

**What is the torque for an M22 12.9 bolt?**
About 971 N·m (716 ft-lb) dry and 728 N·m lubricated.

**What size wrench fits an M22 bolt?**
34 mm for ISO hex bolts and 32 mm for older DIN hex bolts. An M22 socket head cap screw takes a 17 mm hex key.

**What drill size do I need to tap M22?**
Use a 19.5 mm drill for M22 × 2.5 coarse thread.

Source page: https://machinistcharts.com/bolt-torque/m22/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)