# M30 bolt torque

Tighten an M30 × 3.5 class 8.8 bolt to 1,514 N·m (1,116 ft-lb) with dry threads, or 1,135 N·m when lubricated. Class 10.9 takes 2,094 N·m and class 12.9 takes 2,447 N·m.

## M30 × 3.5 torque by property class

| Property class | Dry torque (K 0.20) | Lubricated (K 0.15) | Clamp load | Proof load |
|---|---|---|---|---|
| Class 8.8 | 1,514 N·m (1,116 ft-lb) | 1,135 N·m (837 ft-lb) | 252.3 kN | 336.4 kN |
| Class 10.9 | 2,094 N·m (1,544 ft-lb) | 1,570 N·m (1,158 ft-lb) | 349.0 kN | 465.3 kN |
| Class 12.9 | 2,447 N·m (1,805 ft-lb) | 1,835 N·m (1,354 ft-lb) | 407.8 kN | 543.8 kN |

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

## M30 bolt data

- Thread: M30 × 3.5 coarse
- Tensile stress area: 560.6 mm²
- Wrench: 46 mm (ISO 4014/4017)
- Socket head cap screw hex key: 22 mm
- Tap drill: 26.5 mm
- Clearance hole (ISO 273): 31 close, 33 normal, 35 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 M30 8.8 bolt?**
About 1,514 N·m (1,116 ft-lb) with dry threads and about 1,135 N·m lubricated, based on 75 % of proof load.

**What is the torque for an M30 10.9 bolt?**
About 2,094 N·m (1,544 ft-lb) dry and 1,570 N·m lubricated.

**What is the torque for an M30 12.9 bolt?**
About 2,447 N·m (1,805 ft-lb) dry and 1,835 N·m lubricated.

**What size wrench fits an M30 bolt?**
46 mm for ISO hex bolts. An M30 socket head cap screw takes a 22 mm hex key.

**What drill size do I need to tap M30?**
Use a 26.5 mm drill for M30 × 3.5 coarse thread.

Source page: https://machinistcharts.com/bolt-torque/m30/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)