# M24 bolt torque

Tighten an M24 × 3 class 8.8 bolt to 761 N·m (562 ft-lb) with dry threads, or 571 N·m when lubricated. Class 10.9 takes 1,053 N·m and class 12.9 takes 1,231 N·m.

## M24 × 3 torque by property class

| Property class | Dry torque (K 0.20) | Lubricated (K 0.15) | Clamp load | Proof load |
|---|---|---|---|---|
| Class 8.8 | 761 N·m (562 ft-lb) | 571 N·m (421 ft-lb) | 158.6 kN | 211.5 kN |
| Class 10.9 | 1,053 N·m (777 ft-lb) | 790 N·m (583 ft-lb) | 219.4 kN | 292.6 kN |
| Class 12.9 | 1,231 N·m (908 ft-lb) | 923 N·m (681 ft-lb) | 256.4 kN | 341.9 kN |

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

## M24 bolt data

- Thread: M24 × 3 coarse
- Tensile stress area: 352.5 mm²
- Wrench: 36 mm (ISO 4014/4017)
- Socket head cap screw hex key: 19 mm
- Tap drill: 21 mm
- Clearance hole (ISO 273): 25 close, 26 normal, 28 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 M24 8.8 bolt?**
About 761 N·m (562 ft-lb) with dry threads and about 571 N·m lubricated, based on 75 % of proof load.

**What is the torque for an M24 10.9 bolt?**
About 1,053 N·m (777 ft-lb) dry and 790 N·m lubricated.

**What is the torque for an M24 12.9 bolt?**
About 1,231 N·m (908 ft-lb) dry and 923 N·m lubricated.

**What size wrench fits an M24 bolt?**
36 mm for ISO hex bolts. An M24 socket head cap screw takes a 19 mm hex key.

**What drill size do I need to tap M24?**
Use a 21 mm drill for M24 × 3 coarse thread.

Source page: https://machinistcharts.com/bolt-torque/m24/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)