The short answer
Tighten a 5/8-11 UNC SAE Grade 5 bolt to about 150 ft·lbf (1,801 in·lbf, 203 N·m) with clean, dry threads. That produces about 14,408 lbf of clamp load, 75% of the bolt's proof load. If the threads are oiled or coated with anti-seize, use less torque. See the table below.
Torque by thread condition and preload (ft·lbf)
| Thread condition | K | 60% proof | 75% proof | 90% proof |
|---|---|---|---|---|
| Dry, plain steel | 0.20 | 120 | 150 | 180 |
| Zinc plated | 0.22 | 132 | 165 | 198 |
| Lightly oiled | 0.15 | 90 | 113 | 135 |
| Anti-seize or moly | 0.12 | 72 | 90 | 108 |
The same torque gives very different clamp loads depending on friction. Torquing a lubricated bolt to a dry-thread value can stretch it past yield.
5/8-11 in other grades (dry, 75% proof)
| Grade | Proof strength | Clamp load (lbf) | Torque (ft·lbf) |
|---|---|---|---|
| Grade 2 | 55 ksi | 9,323 | 97 |
| Grade 5 | 85 ksi | 14,408 | 150 |
| Grade 8 | 120 ksi | 20,340 | 212 |
How it's calculated
When the equipment manufacturer publishes a torque, use theirs. Structural bolts (A325/F3125, A490) are installed by turn-of-nut or tension-control methods under the RCSC specification, not by this chart.
Other Grade 5 sizes
1/4-20 · 5/16-18 · 3/8-16 · 7/16-14 · 1/2-13 · 9/16-12 · 3/4-10 · 7/8-9 · 1-8
Open the full bolt torque calculator with these numbers
Results are estimates for planning and education. Verify against the current code edition your jurisdiction has adopted, manufacturer data and a licensed professional before you build or install.