# M16 bolt torque

Tighten an M16 × 2 class 8.8 bolt to 218 N·m (161 ft-lb) with dry threads, or 164 N·m when lubricated. Class 10.9 takes 312 N·m and class 12.9 takes 365 N·m.

## M16 × 2 torque by property class

| Property class | Dry torque (K 0.20) | Lubricated (K 0.15) | Clamp load | Proof load |
|---|---|---|---|---|
| Class 8.8 | 218 N·m (161 ft-lb) | 164 N·m (121 ft-lb) | 68.2 kN | 90.9 kN |
| Class 10.9 | 312 N·m (230 ft-lb) | 234 N·m (173 ft-lb) | 97.5 kN | 130.0 kN |
| Class 12.9 | 365 N·m (269 ft-lb) | 274 N·m (202 ft-lb) | 114.0 kN | 152.0 kN |

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

## M16 bolt data

- Thread: M16 × 2 coarse
- Tensile stress area: 156.7 mm²
- Wrench: 24 mm (ISO 4014/4017)
- Socket head cap screw hex key: 14 mm
- Tap drill: 14 mm
- Clearance hole (ISO 273): 17 close, 17.5 normal, 18.5 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 M16 8.8 bolt?**
About 218 N·m (161 ft-lb) with dry threads and about 164 N·m lubricated, based on 75 % of proof load.

**What is the torque for an M16 10.9 bolt?**
About 312 N·m (230 ft-lb) dry and 234 N·m lubricated.

**What is the torque for an M16 12.9 bolt?**
About 365 N·m (269 ft-lb) dry and 274 N·m lubricated.

**What size wrench fits an M16 bolt?**
24 mm for ISO hex bolts. An M16 socket head cap screw takes a 14 mm hex key.

**What drill size do I need to tap M16?**
Use a 14 mm drill for M16 × 2 coarse thread.

Source page: https://machinistcharts.com/bolt-torque/m16/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)