M12 Grade 12.9 Torque Specification

Torque Values by Surface Condition

Stress area: 84.27 mm² · Proof load: 81,742 N · Clamp load (75%): 61,306 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	147.1	108.5	1301.9	1500.0
Oiled	0.15	110.4	81.4	977.1	1125.8
Zinc Plated	0.18	132.4	97.7	1171.8	1350.1
Waxed	0.1	73.6	54.3	651.4	750.5
MoS₂	0.12	88.3	65.1	781.5	900.4
Galvanized	0.25	183.9	135.6	1627.7	1875.3

Stress area: 92.07 mm² · Proof load: 89,308 N · Clamp load (75%): 66,981 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	160.8	118.6	1423.2	1639.7
Oiled	0.15	120.6	88.9	1067.4	1229.8
Zinc Plated	0.18	144.7	106.7	1280.7	1475.5
Waxed	0.1	80.4	59.3	711.6	819.9
MoS₂	0.12	96.5	71.2	854.1	984.0
Galvanized	0.25	200.9	148.2	1778.1	2048.6

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 970 MPa × 84.27 mm² = 61,306 N

Step 2 — Torque (dry): T = 0.20 × 0.0120 m × 61,306 N = 147.1 N·m

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

Socket head cap screws, racing/motorsport, aerospace, maximum strength applications — highest standard grade

• 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.

SizeM12

Class12.9

Diameter12 mm

Pitch (coarse)1.75 mm

Tensile1220 MPa

Yield1100 MPa

Proof970 MPa