# 5/16 inch bolt torque

Tighten a 5/16-18 UNC grade 5 bolt to 17 ft-lb (24 N·m) with dry threads, or 13 ft-lb when lubricated. Grade 8 takes 25 ft-lb and grade 2 takes 11 ft-lb.

## 5/16 torque by thread series and SAE grade

| Thread | Grade | Dry torque (K 0.20) | Lubricated (K 0.15) | Clamp load |
|---|---|---|---|---|
| 5/16-18 UNC | Grade 2 | 11 ft-lb (15 N·m) | 8.4 ft-lb | 2,163 lbf |
| 5/16-18 UNC | Grade 5 | 17 ft-lb (24 N·m) | 13 ft-lb | 3,342 lbf |
| 5/16-18 UNC | Grade 8 | 25 ft-lb (33 N·m) | 18 ft-lb | 4,719 lbf |
| 5/16-24 UNF | Grade 2 | 12 ft-lb (17 N·m) | 9.4 ft-lb | 2,395 lbf |
| 5/16-24 UNF | Grade 5 | 19 ft-lb (26 N·m) | 14 ft-lb | 3,702 lbf |
| 5/16-24 UNF | Grade 8 | 27 ft-lb (37 N·m) | 20 ft-lb | 5,226 lbf |

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

## 5/16 bolt data

- Threads: 5/16-18 UNC, 5/16-24 UNF
- Wrench: 1/2 in
- Tap drill: F (0.2570 in) for UNC, I (0.2720 in) for UNF

## Method

Proof strength from SAE J429 × tensile stress area As = 0.7854 × (D − 0.9743/n)² (ASME B1.1). F = 75 % of proof load. T = K × F × D with K = 0.20 dry, 0.15 lubricated.

## FAQ

**What is the torque for a 5/16 grade 5 bolt?**
About 17 ft-lb dry for 5/16-18 UNC and 19 ft-lb for 5/16-24 UNF, based on 75 % of proof load.

**What is the torque for a 5/16 grade 8 bolt?**
About 25 ft-lb dry for 5/16-18 UNC and 27 ft-lb for 5/16-24 UNF.

**What is the torque for a 5/16 grade 2 bolt?**
About 11 ft-lb dry for 5/16-18 UNC.

**What size wrench fits a 5/16 bolt?**
A standard 5/16" hex cap screw takes a 1/2" wrench or socket.

Source page: https://machinistcharts.com/bolt-torque/5-16-inch/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)