# M5 bolt torque

Tighten an M5 × 0.8 class 8.8 bolt to 6.2 N·m (4.6 ft-lb) with dry threads, or 4.6 N·m when lubricated. Class 10.9 takes 8.8 N·m and class 12.9 takes 10 N·m.

## M5 × 0.8 torque by property class

| Property class | Dry torque (K 0.20) | Lubricated (K 0.15) | Clamp load | Proof load |
|---|---|---|---|---|
| Class 8.8 | 6.2 N·m (4.6 ft-lb) | 4.6 N·m (3.4 ft-lb) | 6.2 kN | 8.2 kN |
| Class 10.9 | 8.8 N·m (6.5 ft-lb) | 6.6 N·m (4.9 ft-lb) | 8.8 kN | 11.8 kN |
| Class 12.9 | 10 N·m (7.6 ft-lb) | 7.7 N·m (5.7 ft-lb) | 10.3 kN | 13.8 kN |

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

## M5 bolt data

- Thread: M5 × 0.8 coarse
- Tensile stress area: 14.2 mm²
- Wrench: 8 mm (ISO 4014/4017)
- Socket head cap screw hex key: 4 mm
- Tap drill: 4.2 mm
- Clearance hole (ISO 273): 5.3 close, 5.5 normal, 5.8 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 M5 8.8 bolt?**
About 6.2 N·m (4.6 ft-lb) with dry threads and about 4.6 N·m lubricated, based on 75 % of proof load.

**What is the torque for an M5 10.9 bolt?**
About 8.8 N·m (6.5 ft-lb) dry and 6.6 N·m lubricated.

**What is the torque for an M5 12.9 bolt?**
About 10 N·m (7.6 ft-lb) dry and 7.7 N·m lubricated.

**What size wrench fits an M5 bolt?**
8 mm for ISO hex bolts. An M5 socket head cap screw takes a 4 mm hex key.

**What drill size do I need to tap M5?**
Use a 4.2 mm drill for M5 × 0.8 coarse thread.

Source page: https://machinistcharts.com/bolt-torque/m5/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)