In Brief: SAE Bolt Torque Chart – Grade 2, Grade 5, Grade 8
SAE bolt grades indicate the strength of the bolt. Each bolt grade has an ideal tightening torque for maximum clamping force without breaking. Grade 2 bolts are cheap but not very strong, grade 8 bolts are the strongest and most expensive, and grade 5 bolts are the most common. Refer to the charts to find the ideal tightening torque.
The grading indicates the material strength of the bolt.
The higher the grade, the stronger the bolt. The most common SAE bolt grades are Grade 2, Grade 5, and Grade 8.
Very few applications outside of industry require higher than a Grade 8 bolt.
For a rundown of the different grading systems and what they mean, check out this video from The Home Depot:
You can tell which bolt you are working with by the markings on the head. Compare the bolts you have with the diagrams below, then refer to the appropriate chart to see the ideal tightening torque.
Bolt Torque Charts for Grades 2, 5, and 8
Bolts must be tightened using the correct torque. Properly torqued bolts will provide the maximum amount of clamping force under load.
Under torqued bolts can quickly come loose, and over-torqued bolts are liable to break.
The charts below show the ideal tightening torque for each bolt grade for a variety of sizes.
The size column also includes the thread count. Identify the grade, size, and thread density of your bolts and refer to the tightening torque columns.
The “wet” column indicates lubricated bolts, whereas the “dry” column indicated unlubricated bolts.
SAE Grade 2 Bolt Torque Chart
Grade 2 bolts are used for applications that require fastening but do not require the bolt to undergo heavy load.
They are more affordable but lack the strength needed for structural applications.
They bear no head markings and are made from low or medium carbon steel.
They have a proof load of 55000 psi, minimum yield strength of 57000 psi, and a minimum tensile strength of 74000 psi.
Table 1 – SAE Grade 2 Bolt Torque Chart
| Size | Tightening Torque (Wet) / lb-ft | Tightening Torque (Dry) / lb-ft |
|---|---|---|
| 1/4-20 | 4 | 5.5 |
| 1/4-28 | 4.7 | 6.3 |
| 5/16-18 | 8 | 11 |
| 5/16-24 | 9 | 12 |
| 3/8-16 | 15 | 20 |
| 3/8-24 | 17 | 23 |
| 7/16-14 | 24 | 30 |
| 7/16-20 | 25 | 35 |
| 1/2-13 | 35 | 50 |
| 1/2-20 | 40 | 55 |
| 9/16-12 | 55 | 70 |
| 9/16-18 | 60 | 80 |
| 5/8-11 | 75 | 100 |
| 5/8-18 | 85 | 110 |
| 3/4-10 | 130 | 175 |
| 3/4-16 | 145 | 195 |
SAE Grade 5 Bolt Torque Chart
Grade 5 bolts offer more strength and corrosion resistance than the grade 2 bolts and tend to see more use even though they cost a bit more. Most of the time, you will want to use grade 5 bolts.
They are made from quenched and tempered medium carbon steel and bear a 3-line mark on the head.
They have a proof load of 85000 psi, minimum yield strength of 92000 psi, and a minimum tensile strength of 120000 psi.
Table 1 – SAE Grade 5 Bolt Torque Chart
| Size | Tightening Torque (Wet) / lb-ft | Tightening Torque (Dry) / lb-ft |
|---|---|---|
| 1/4-20 | 6.3 | 8 |
| 1/4-28 | 7.2 | 10 |
| 5/16-18 | 13 | 17 |
| 5/16-24 | 14 | 19 |
| 3/8-16 | 23 | 30 |
| 3/8-24 | 25 | 35 |
| 7/16-14 | 35 | 50 |
| 7/16-20 | 40 | 55 |
| 1/2-13 | 55 | 75 |
| 1/2-20 | 65 | 90 |
| 9/16-12 | 80 | 110 |
| 9/16-18 | 90 | 120 |
| 5/8-11 | 110 | 150 |
| 5/8-18 | 130 | 170 |
| 3/4-10 | 200 | 260 |
| 3/4-16 | 220 | 300 |
SAE Grade 8 Bolt Torque Chart
Grade 8 bolts are the strongest commonly used bolts outside of industrial applications.
They are durable, strong, and can resist a heavy amount of stress. For those reasons, these are the bolts often used in military and aerospace applications.
They are made of medium carbon alloy steel and have 6 line marks on the head.
They have a proof load of 120000 psi, minimum yield strength of 130000 psi, and a minimum tensile strength of 150000 psi.
Table 3 – SAE Grade 8 Bolt Torque Chart
| Size | Tightening Torque (Wet) / lb-ft | Tightening Torque (Dry) / lb-ft |
|---|---|---|
| 1/4-20 | 9 | 12 |
| 1/4-28 | 10 | 14 |
| 5/16-18 | 18 | 25 |
| 5/16-24 | 20 | 25 |
| 3/8-16 | 35 | 45 |
| 3/8-24 | 35 | 50 |
| 7/16-14 | 55 | 70 |
| 7/16-20 | 60 | 80 |
| 1/2-13 | 80 | 110 |
| 1/2-20 | 90 | 120 |
| 9/16-12 | 110 | 150 |
| 9/16-18 | 130 | 170 |
| 5/8-11 | 170 | 220 |
| 5/8-18 | 180 | 240 |
| 3/4-10 | 280 | 380 |
| 3/4-16 | 320 | 420 |
Summary
We hope this guide on SAE bolt tightening torques has helped you with your project.
Keep this page bookmarked so that you can quickly refer to it the next time you need to know the best tightening torque for SAE bolt grades 2, 5, and 8.
If you have any questions or comments about this guide or bolt torque in general, please feel free to leave them in the section below.