# 3/4 inch bolt torque

Tighten a 3/4-10 UNC grade 5 bolt to 267 ft-lb (361 N·m) with dry threads, or 200 ft-lb when lubricated. Grade 8 takes 376 ft-lb and grade 2 takes 172 ft-lb.

## 3/4 torque by thread series and SAE grade

| Thread | Grade | Dry torque (K 0.20) | Lubricated (K 0.15) | Clamp load |
|---|---|---|---|---|
| 3/4-10 UNC | Grade 2 | 172 ft-lb (234 N·m) | 129 ft-lb | 13,797 lbf |
| 3/4-10 UNC | Grade 5 | 267 ft-lb (361 N·m) | 200 ft-lb | 21,322 lbf |
| 3/4-10 UNC | Grade 8 | 376 ft-lb (510 N·m) | 282 ft-lb | 30,101 lbf |
| 3/4-16 UNF | Grade 2 | 192 ft-lb (261 N·m) | 144 ft-lb | 15,385 lbf |
| 3/4-16 UNF | Grade 5 | 297 ft-lb (403 N·m) | 223 ft-lb | 23,776 lbf |
| 3/4-16 UNF | Grade 8 | 420 ft-lb (569 N·m) | 315 ft-lb | 33,566 lbf |

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

## 3/4 bolt data

- Threads: 3/4-10 UNC, 3/4-16 UNF
- Wrench: 1-1/8 in
- Tap drill: 21/32 (0.6563 in) for UNC, 11/16 (0.6875 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 3/4 grade 5 bolt?**
About 267 ft-lb dry for 3/4-10 UNC and 297 ft-lb for 3/4-16 UNF, based on 75 % of proof load.

**What is the torque for a 3/4 grade 8 bolt?**
About 376 ft-lb dry for 3/4-10 UNC and 420 ft-lb for 3/4-16 UNF.

**What is the torque for a 3/4 grade 2 bolt?**
About 172 ft-lb dry for 3/4-10 UNC.

**What size wrench fits a 3/4 bolt?**
A standard 3/4" hex cap screw takes a 1-1/8" wrench or socket.

Source page: https://machinistcharts.com/bolt-torque/3-4-inch/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)