M5 Grade 5.8 Torque Specification

Torque Values by Surface Condition

Stress area: 14.18 mm² · Proof load: 5,388 N · Clamp load (75%): 4,041 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	4.0	3.0	35.4	40.8
Oiled	0.15	3.0	2.2	26.6	30.6
Zinc Plated	0.18	3.6	2.7	31.9	36.7
Waxed	0.1	2.0	1.5	17.7	20.4
MoS₂	0.12	2.4	1.8	21.2	24.5
Galvanized	0.25	5.1	3.8	45.1	52.0

Stress area: 16.13 mm² · Proof load: 6,129 N · Clamp load (75%): 4,597 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	4.6	3.4	40.7	46.9
Oiled	0.15	3.4	2.5	30.1	34.7
Zinc Plated	0.18	4.1	3.0	36.3	41.8
Waxed	0.1	2.3	1.7	20.4	23.5
MoS₂	0.12	2.8	2.1	24.8	28.6
Galvanized	0.25	5.7	4.2	50.4	58.1

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 380 MPa × 14.18 mm² = 4,041 N

Step 2 — Torque (dry): T = 0.20 × 0.0050 m × 4,041 N = 4.0 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.

SizeM5

Class5.8

Diameter5 mm

Pitch (coarse)0.8 mm

Tensile520 MPa

Yield420 MPa

Proof380 MPa