# M6 bolt torque

Tighten an M6 × 1 class 8.8 bolt to 11 N·m (7.7 ft-lb) with dry threads, or 7.9 N·m when lubricated. Class 10.9 takes 15 N·m and class 12.9 takes 18 N·m.

## M6 × 1 torque by property class

| Property class | Dry torque (K 0.20) | Lubricated (K 0.15) | Clamp load | Proof load |
|---|---|---|---|---|
| Class 8.8 | 11 N·m (7.7 ft-lb) | 7.9 N·m (5.8 ft-lb) | 8.8 kN | 11.7 kN |
| Class 10.9 | 15 N·m (11 ft-lb) | 11 N·m (8.3 ft-lb) | 12.5 kN | 16.7 kN |
| Class 12.9 | 18 N·m (13 ft-lb) | 13 N·m (9.7 ft-lb) | 14.6 kN | 19.5 kN |

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

## M6 bolt data

- Thread: M6 × 1 coarse
- Tensile stress area: 20.1 mm²
- Wrench: 10 mm (ISO 4014/4017)
- Socket head cap screw hex key: 5 mm
- Tap drill: 5 mm
- Clearance hole (ISO 273): 6.4 close, 6.6 normal, 7 loose (mm)

## Method

Proof stress from ISO 898-1 (580 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 M6 8.8 bolt?**
About 11 N·m (7.7 ft-lb) with dry threads and about 7.9 N·m lubricated, based on 75 % of proof load.

**What is the torque for an M6 10.9 bolt?**
About 15 N·m (11 ft-lb) dry and 11 N·m lubricated.

**What is the torque for an M6 12.9 bolt?**
About 18 N·m (13 ft-lb) dry and 13 N·m lubricated.

**What size wrench fits an M6 bolt?**
10 mm for ISO hex bolts. An M6 socket head cap screw takes a 5 mm hex key.

**What drill size do I need to tap M6?**
Use a 5 mm drill for M6 × 1 coarse thread.

Source page: https://machinistcharts.com/bolt-torque/m6/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)