9/16 inch bolt torque
A 9/16-12 bolt takes 70 ft-lb in Grade 2, 109 in Grade 5 and 154 in Grade 8, dry, at 75% of proof load; the 9/16-18 fine thread takes 79, 121 and 171. Oiled threads take a quarter less.
Sources checked
| Thread | Grade | DryK 0.20 | Zinc platedK 0.20 | OiledK 0.15 | WaxedK 0.10 | Clamp load |
|---|---|---|---|---|---|---|
| 9/16-12UNC (coarse) | Grade 2 | 70.495.4 | 70.495.4 | 52.871.6 | 35.247.7 | 7,508 lbf33.4 kN |
| Grade 5 | 109147 | 109147 | 81.6111 | 54.473.7 | 11,603 lbf51.6 kN | |
| Grade 8 | 154208 | 154208 | 115156 | 76.8104 | 16,380 lbf72.9 kN | |
| 9/16-18UNF (fine) | Grade 2 | 78.5106 | 78.5106 | 58.979.8 | 39.353.2 | 8,374 lbf37.2 kN |
| Grade 5 | 121164 | 121164 | 91.0123 | 60.782.2 | 12,941 lbf57.6 kN | |
| Grade 8 | 171232 | 171232 | 128174 | 85.6116 | 18,270 lbf81.3 kN |
Work out 9/16 inch torque
Change grade, threads or preload
9/16-12 Grade 5, dry, plain steel
109ft-lb147N·m
- Clamp load
- 11,603 lbf (51.6 kN)
- Proof load
- 15,470 lbf
The working
- Tensile stress area. A = 0.7854 × (D − 0.9743 ÷ n)² = 0.7854 × (0.5625 − 0.9743 ÷ 12)² = 0.182 in²
- Proof load. Grade 5 proof stress is 85,000 psi, so A × stress = 15,470 lbf.
- Clamp load. 75% of proof load = 11,603 lbf.
- Torque. T = K × D × F = 0.2 × 0.5625 in × 11,603 lbf = 1,305 in-lb ÷ 12 = 109 ft-lb (147 N·m).
Where the 9/16-12 numbers come from
The 9/16-12 UNC (coarse) thread has a tensile stress area of 0.182 in². A Grade 8 bolt’s proof stress is 120,000 psi, so its proof load is 21,840 lbf, and 75% of that is a clamp load of 16,380 lbf.
Torque = K × D × F = 0.20 × 0.5625 in × 16,380 lbf = 1,843 in-lb, or 154 ft-lb (208 N·m) dry. With oil (K 0.15) it’s 115 ft-lb (156 N·m).
Other sizes
All sizes on one page: the SAE bolt torque chart.
Questions
What torque for a 9/16-12 Grade 8 bolt?
154 ft-lb (208 N·m) dry and 115 ft-lb (156 N·m) oiled, at 75% of proof load. That clamps the joint with 16,380 lbf (72.9 kN).
What torque for a 9/16-12 Grade 5 bolt?
109 ft-lb (147 N·m) dry, at 75% of proof load; a quarter less with oiled threads.
Coarse or fine thread?
Use whichever the bolt has. The fine 9/16-18 thread has a bigger stress area than the coarse one, so it takes slightly more torque for the same clamp. A thread gauge settles it.
Does this apply to wheel nuts or engine bolts?
No. Use the vehicle maker’s value for those: see lug nut torque by vehicle. These numbers are for general-purpose steel bolts where no spec exists.
Sources
- Portland Bolt: SAE J429: proof load, yield and tensile strength for Grades 2, 5 and 8 (checked October 14, 2026)
- Portland Bolt: Thread pitch chart: UNC and UNF threads per inch and tensile stress areas (checked October 14, 2026)
- Fastenal: Mechanical properties of inch fasteners, with UNC and UNF tensile stress areas (checked October 14, 2026)
- Engineering Toolbox: Threaded bolts: tensile stress area formulas for unified and ISO metric threads (checked October 14, 2026)
- Fastenal: Torque–tension relationship for A307 A, Grade 5, 8 and 9 coarse thread bolts (75% of proof load; K 0.15 and 0.20) (checked October 14, 2026)
- Portland Bolt: Bolt torque chart: T = KDP at 75% of proof load, with K for plain, waxed and galvanized bolts (checked October 14, 2026)
Spotted a number that doesn’t match your manual or a source? Tell us; corrections are logged on the sources page.