Complete Torque Chart for Class 8.8, 10.9, and 12.9 Metric Fasteners

Metric Bolt Torque Chart

Complete torque specifications for Class 8.8, 10.9, and 12.9 metric fasteners with easy property class decoding.

Metric fasteners use a two-digit property class system that directly indicates strength. These torque values are calculated at 75% of proof load for reliable joint performance.

Understanding Property Classes

8.8

Standard Grade

Equivalent to SAE Grade 5

Tensile Strength800 MPa
Proof Load640 MPa
PSI Equivalent116,000 PSI
10.9

High Strength

Equivalent to SAE Grade 8

Tensile Strength1,040 MPa
Proof Load940 MPa
PSI Equivalent151,000 PSI
12.9

Ultra High Strength

Exceeds Grade 8

Tensile Strength1,220 MPa
Proof Load1,100 MPa
PSI Equivalent177,000 PSI

🔢 Decoding the Numbers

The property class marking tells you everything about the fastener's strength:

10.9
First digit × 100 = Tensile strength in MPa (10 × 100 = 1,000 MPa)
First digit × Second digit × 10 = Proof load in MPa (10 × 9 × 10 = 900 MPa)

Note: Actual minimums slightly exceed calculated values (e.g., 10.9 = 1,040 MPa tensile, 940 MPa proof)

Class 8.8 Torque Specifications

💡 About Class 8.8

Class 8.8 is the most common metric grade, used for general industrial and automotive applications. Equivalent to SAE Grade 5 in strength.

Size Pitch Dry Torque
(Nm)		 Dry Torque
(ft-lbs)		 Lubricated
(Nm)		 Lubricated
(ft-lbs)		 Clamp Load
(kN)
M3 0.5 1.0 0.7 0.8 0.6 2.1
M4 0.7 2.5 1.8 1.9 1.4 3.9
M5 0.8 4.9 3.6 3.7 2.7 6.1
M6 1.0 8.5 6.3 6.4 4.7 8.8
M8 1.25 21 15 16 12 16.2
M10 1.5 41 30 31 23 25.5
M12 1.75 71 52 53 39 36.8
M14 2.0 115 85 86 63 51.0
M16 2.0 175 129 131 97 68.0
M18 2.5 245 181 184 136 84.5
M20 2.5 350 258 263 194 108.5
M22 2.5 470 347 353 260 133.0
M24 3.0 600 443 450 332 156.0

Class 10.9 Torque Specifications

💡 About Class 10.9

Class 10.9 is a high-strength grade for demanding applications. Equivalent to SAE Grade 8 — use for critical automotive, heavy machinery, and structural connections.

Size Pitch Dry Torque
(Nm)		 Dry Torque
(ft-lbs)		 Lubricated
(Nm)		 Lubricated
(ft-lbs)		 Clamp Load
(kN)
M3 0.5 1.5 1.1 1.1 0.8 3.1
M4 0.7 3.6 2.7 2.7 2.0 5.7
M5 0.8 7.2 5.3 5.4 4.0 9.0
M6 1.0 12 9 9 7 13.0
M8 1.25 31 23 23 17 24.0
M10 1.5 60 44 45 33 37.5
M12 1.75 105 77 79 58 54.0
M14 2.0 170 125 128 94 75.0
M16 2.0 260 192 195 144 100.0
M18 2.5 360 266 270 199 124.0
M20 2.5 510 376 383 282 159.0
M22 2.5 690 509 518 382 196.0
M24 3.0 880 649 660 487 229.0

Class 12.9 Torque Specifications

⚠️ About Class 12.9

Class 12.9 is ultra-high strength — use only where specified by engineering. These fasteners are less ductile and more susceptible to hydrogen embrittlement. Requires careful handling and proper torque procedures.

Size Pitch Dry Torque
(Nm)		 Dry Torque
(ft-lbs)		 Lubricated
(Nm)		 Lubricated
(ft-lbs)		 Clamp Load
(kN)
M3 0.5 1.8 1.3 1.4 1.0 3.7
M4 0.7 4.3 3.2 3.2 2.4 6.8
M5 0.8 8.6 6.3 6.5 4.8 10.8
M6 1.0 15 11 11 8 15.5
M8 1.25 37 27 28 21 28.5
M10 1.5 72 53 54 40 45.0
M12 1.75 125 92 94 69 65.0
M14 2.0 200 148 150 111 90.0
M16 2.0 310 229 233 172 120.0
M18 2.5 430 317 323 238 149.0
M20 2.5 610 450 458 338 190.0
M22 2.5 820 605 615 454 234.0
M24 3.0 1050 775 788 581 274.0

Metric to SAE Comparison

Metric Class SAE Grade Tensile Strength Common Uses
4.6 Grade 2 400 MPa / 58,000 PSI Light duty, non-critical
8.8 Grade 5 800 MPa / 116,000 PSI General automotive, construction
10.9 Grade 8 1,040 MPa / 151,000 PSI High-stress, critical applications
12.9 Above Grade 8 1,220 MPa / 177,000 PSI Maximum strength requirements

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