# M12 bolt torque

Tighten an M12 × 1.75 class 8.8 bolt to 88 N·m (65 ft-lb) with dry threads, or 66 N·m when lubricated. Class 10.9 takes 126 N·m and class 12.9 takes 147 N·m.

## M12 × 1.75 torque by property class

| Property class | Dry torque (K 0.20) | Lubricated (K 0.15) | Clamp load | Proof load |
|---|---|---|---|---|
| Class 8.8 | 88 N·m (65 ft-lb) | 66 N·m (49 ft-lb) | 36.7 kN | 48.9 kN |
| Class 10.9 | 126 N·m (93 ft-lb) | 94 N·m (70 ft-lb) | 52.5 kN | 69.9 kN |
| Class 12.9 | 147 N·m (109 ft-lb) | 110 N·m (81 ft-lb) | 61.3 kN | 81.7 kN |

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

## M12 bolt data

- Thread: M12 × 1.75 coarse
- Tensile stress area: 84.3 mm²
- Wrench: 18 mm (ISO 4014/4017), 19 mm (DIN 931/933)
- Socket head cap screw hex key: 10 mm
- Tap drill: 10.2 mm
- Clearance hole (ISO 273): 13 close, 13.5 normal, 14.5 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 M12 8.8 bolt?**
About 88 N·m (65 ft-lb) with dry threads and about 66 N·m lubricated, based on 75 % of proof load.

**What is the torque for an M12 10.9 bolt?**
About 126 N·m (93 ft-lb) dry and 94 N·m lubricated.

**What is the torque for an M12 12.9 bolt?**
About 147 N·m (109 ft-lb) dry and 110 N·m lubricated.

**What size wrench fits an M12 bolt?**
18 mm for ISO hex bolts and 19 mm for older DIN hex bolts. An M12 socket head cap screw takes a 10 mm hex key.

**What drill size do I need to tap M12?**
Use a 10.2 mm drill for M12 × 1.75 coarse thread.

Source page: https://machinistcharts.com/bolt-torque/m12/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)