M4 Grade 5.8 Torque Specification

Torque Values by Surface Condition

Stress area: 8.78 mm² · Proof load: 3,336 N · Clamp load (75%): 2,502 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2.0	1.5	17.7	20.4
Oiled	0.15	1.5	1.1	13.3	15.3
Zinc Plated	0.18	1.8	1.3	15.9	18.4
Waxed	0.1	1.0	0.7	8.9	10.2
MoS₂	0.12	1.2	0.9	10.6	12.2
Galvanized	0.25	2.5	1.8	22.1	25.5

Stress area: 9.79 mm² · Proof load: 3,720 N · Clamp load (75%): 2,790 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2.2	1.6	19.5	22.4
Oiled	0.15	1.7	1.3	15.0	17.3
Zinc Plated	0.18	2.0	1.5	17.7	20.4
Waxed	0.1	1.1	0.8	9.7	11.2
MoS₂	0.12	1.3	1.0	11.5	13.3
Galvanized	0.25	2.8	2.1	24.8	28.6

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 380 MPa × 8.78 mm² = 2,502 N

Step 2 — Torque (dry): T = 0.20 × 0.0040 m × 2,502 N = 2.0 N·m

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

General industrial fastening, equipment mounting, moderate structural loads

• 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

Class5.8

Diameter4 mm

Pitch (coarse)0.7 mm

Tensile520 MPa

Yield420 MPa

Proof380 MPa