A 1/2-inch Grade 2 bolt takes 48.8 ft·lbs (66.2 N·m) dry, or 36.6 ft·lbs oiled. Every size in the range is listed below — click a value for the full spec including all six surface conditions and fine-thread figures.
| Size | TPI (UNC) | ft·lbs (dry) | N·m (dry) | ft·lbs (oiled) |
|---|---|---|---|---|
| #6 | 32 | 0.9 | 1.2 | 0.6 |
| #8 | 32 | 1.6 | 2.2 | 1.2 |
| #10 | 24 | 2.3 | 3.1 | 1.7 |
| 1/4" | 20 | 5.5 | 7.5 | 4.1 |
| 5/16" | 18 | 11.3 | 15.3 | 8.4 |
| 3/8" | 16 | 20.0 | 27.1 | 15.0 |
| 7/16" | 14 | 32.0 | 43.4 | 24.0 |
| 1/2" | 13 | 48.8 | 66.2 | 36.6 |
| 9/16" | 12 | 70.4 | 95.4 | 52.8 |
| 5/8" | 11 | 97.1 | 131.7 | 72.8 |
| 3/4" | 10 | 172.2 | 233.5 | 129.2 |
| 7/8" | 9 | 166.7 | 226.0 | 125.1 |
| 1" | 8 | 250.0 | 339.0 | 187.5 |
| 1-1/8" | 7 | 354.1 | 480.1 | 265.6 |
| 1-1/4" | 7 | 499.6 | 677.4 | 374.7 |
| 1-3/8" | 6 | 655.1 | 888.2 | 491.3 |
| 1-1/2" | 6 | 869.4 | 1178.7 | 652.0 |
Dry/plain steel, K = 0.20 · UNC coarse thread · Clamp load 75% of proof load · Click any ft·lbs value for full details
Identification: No radial lines on the head. Head markings are the only reliable way to tell grades apart — plating and finish tell you nothing about strength.
Material and strength: Low or medium carbon steel, as-rolled. Tensile strength 74,000 psi (60,000 psi above 3/4"), proof load 55,000 psi (33,000 psi above 3/4") per SAE J429.
Where it is used: General-purpose hardware — brackets, panels, guards and non-structural assemblies where clamp load is not critical.
Worth knowing: Grade 2 strength drops above 3/4 inch: proof stress falls from 55,000 to 33,000 psi, which is why the 7/8-inch torque figure is lower than the 3/4-inch one.
Every figure comes from T = K × D × F, where K is the nut factor (0.20 dry, 0.15 oiled), D is nominal diameter, and F is clamp load set at 75% of the bolt's proof load. Proof stress and tensile stress area come from SAE J429.
These are engineering reference values for a standard hex bolt in a steel joint. Where a manufacturer publishes a specific figure for an assembly, that figure takes precedence. Full methodology →
It depends on diameter. A 1/4-inch Grade 2 takes 5.5 ft·lbs, a 1/2-inch takes 48.8 ft·lbs, and a 3/4-inch takes 172.2 ft·lbs — all dry, plain steel, UNC coarse thread. The full table on this page covers #6 through 1-1/2 inch.
No radial lines on the head. Head markings are the only reliable way to identify grade — never assume from appearance or plating.
Low or medium carbon steel, as-rolled, with a tensile strength of 74,000 psi (60,000 psi above 3/4") and a proof load of 55,000 psi (33,000 psi above 3/4") per SAE J429.
Yes. Lubrication cuts the friction coefficient from about 0.20 to 0.15, so the same clamp load needs roughly 25% less torque. A 1/2-inch Grade 2 goes from 48.8 ft·lbs dry to 36.6 ft·lbs oiled.