#10 Grade 2 Bolt Torque: 2.3 ft·lbs / 3.1 N·m

Torque Values by Surface Condition

UNC — Coarse Thread — 24 TPI

Stress area: 0.0175 in² · Proof load: 963 lbs · Clamp load (75%): 722 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	2.29	3.10	27.4	31.6
Oiled	0.15	1.71	2.32	20.6	23.7
Zinc Plated	0.18	2.06	2.79	24.7	28.4
Waxed	0.1	1.14	1.55	13.7	15.8
MoS₂	0.12	1.37	1.86	16.5	19.0
Galvanized	0.25	2.86	3.87	34.3	39.5

UNF — Fine Thread — 32 TPI

Stress area: 0.02 in² · Proof load: 1,100 lbs · Clamp load (75%): 825 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	2.61	3.54	31.4	36.1
Oiled	0.15	1.96	2.66	23.5	27.1
Zinc Plated	0.18	2.35	3.19	28.2	32.5
Waxed	0.1	1.31	1.77	15.7	18.1
MoS₂	0.12	1.57	2.13	18.8	21.7
Galvanized	0.25	3.27	4.43	39.2	45.1

Torque by surface condition

UNC thread, ft·lbs. Values from the table above.

Same bolt, same target clamp load: thread friction alone moves the required torque from 1.14 ft·lbs (waxed) to 2.86 ft·lbs (hot-dip galvanized), 2.5× as much. Match the row to the fastener's actual finish and lubrication.

How This Value Is Calculated

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 55,000 psi × 0.0175 in² = 722 lbs

Step 2 — Torque (dry): T = 0.20 × 0.19 in × 722 lbs ÷ 12 = 2.3 ft·lbs

Proof stress per SAE J429 Table 3. Stress area per ASME B1.1. Typical K-factor, consistent with VDI 2230 friction values. SAE J429 formally covers 1/4" to 1-1/2" diameters; for numbered machine screws these figures apply the same grade proof stress (as used for Grade 5/8 machine screws sold to SAE-equivalent strength) — check the screw supplier's rating.

When to Use Grade 2

General-purpose, non-critical bolting. Most common ungraded hardware-store bolts.

Important Notes

• Torque values are for standard hex bolts with unified threads per ASME B1.1. Socket head cap screws may have different requirements.
• Lubrication reduces required torque significantly — using dry torque values on lubricated bolts risks exceeding yield strength.
• For critical or safety-related applications, always consult the manufacturer's specifications or applicable design standard.
• Re-used bolts may have altered friction characteristics. Inspect threads before reuse.

Specifications

Size#10

Grade2

Diameter0.19" (4.83 mm)

TPI (UNC)24

Tensile74,000 psi

Yield57,000 psi

Proof55,000 psi

#10 Grade 2 Torque Spec