M4 Grade 4.6 Torque Specification

Torque Values by Surface Condition

Stress area: 8.78 mm² · Proof load: 1,975 N · Clamp load (75%): 1,482 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1.2	0.9	10.6	12.2
Oiled	0.15	0.9	0.7	8.0	9.2
Zinc Plated	0.18	1.1	0.8	9.7	11.2
Waxed	0.1	0.6	0.4	5.3	6.1
MoS₂	0.12	0.7	0.5	6.2	7.1
Galvanized	0.25	1.5	1.1	13.3	15.3

Stress area: 9.79 mm² · Proof load: 2,203 N · Clamp load (75%): 1,652 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1.3	1.0	11.5	13.3
Oiled	0.15	1.0	0.7	8.9	10.2
Zinc Plated	0.18	1.2	0.9	10.6	12.2
Waxed	0.1	0.7	0.5	6.2	7.1
MoS₂	0.12	0.8	0.6	7.1	8.2
Galvanized	0.25	1.7	1.3	15.0	17.3

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 225 MPa × 8.78 mm² = 1,482 N

Step 2 — Torque (dry): T = 0.20 × 0.0040 m × 1,482 N = 1.2 N·m

Proof stress per ISO 898-1:2013 Table 4. Stress area per ISO 898-1 Annex A. K-factor per VDI 2230.

Non-critical assemblies, light-duty applications, general-purpose hardware where high strength is not required

• Torque values are for standard hex bolts with ISO metric threads. 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 (e.g., VDI 2230).
• Re-used bolts may have altered friction characteristics. Inspect threads before reuse.

SizeM4

Class4.6

Diameter4 mm

Pitch (coarse)0.7 mm

Tensile400 MPa

Yield240 MPa

Proof225 MPa