5/8 inch bolt torque
A 5/8-11 bolt takes 97 ft-lb in Grade 2, 150 in Grade 5 and 212 in Grade 8, dry, at 75% of proof load; the 5/8-18 fine thread takes 110, 170 and 240. 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 |
|---|---|---|---|---|---|---|
| 5/8-11UNC (coarse) | Grade 2 | 97.1132 | 97.1132 | 72.898.7 | 48.665.8 | 9,323 lbf41.5 kN |
| Grade 5 | 150203 | 150203 | 113153 | 75.0102 | 14,408 lbf64.1 kN | |
| Grade 8 | 212287 | 212287 | 159215 | 106144 | 20,340 lbf90.5 kN | |
| 5/8-18UNF (fine) | Grade 2 | 110149 | 110149 | 82.5112 | 55.074.6 | 10,560 lbf47.0 kN |
| Grade 5 | 170230 | 170230 | 128173 | 85.0115 | 16,320 lbf72.6 kN | |
| Grade 8 | 240325 | 240325 | 180244 | 120163 | 23,040 lbf102.5 kN |
Work out 5/8 inch torque
Change grade, threads or preload
5/8-11 Grade 5, dry, plain steel
150ft-lb203N·m
- Clamp load
- 14,408 lbf (64.1 kN)
- Proof load
- 19,210 lbf
The working
- Tensile stress area. A = 0.7854 × (D − 0.9743 ÷ n)² = 0.7854 × (0.625 − 0.9743 ÷ 11)² = 0.226 in²
- Proof load. Grade 5 proof stress is 85,000 psi, so A × stress = 19,210 lbf.
- Clamp load. 75% of proof load = 14,408 lbf.
- Torque. T = K × D × F = 0.2 × 0.625 in × 14,408 lbf = 1,801 in-lb ÷ 12 = 150 ft-lb (203 N·m).
Where the 5/8-11 numbers come from
The 5/8-11 UNC (coarse) thread has a tensile stress area of 0.226 in². A Grade 8 bolt’s proof stress is 120,000 psi, so its proof load is 27,120 lbf, and 75% of that is a clamp load of 20,340 lbf.
Torque = K × D × F = 0.20 × 0.625 in × 20,340 lbf = 2,543 in-lb, or 212 ft-lb (287 N·m) dry. With oil (K 0.15) it’s 159 ft-lb (215 N·m).
Other sizes
All sizes on one page: the SAE bolt torque chart.
Questions
What torque for a 5/8-11 Grade 8 bolt?
212 ft-lb (287 N·m) dry and 159 ft-lb (215 N·m) oiled, at 75% of proof load. That clamps the joint with 20,340 lbf (90.5 kN).
What torque for a 5/8-11 Grade 5 bolt?
150 ft-lb (203 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 5/8-18 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.