Metric Bolt Torque Chart — Class 8.8, 10.9 & 12.9 (M4–M30)
Metric coarse-thread calculated examples in Nm and ft-lb. Review the assumptions and source limitations before using any general torque reference; use the manufacturer’s specification for your actual joint.
Metric bolt torque chart (PDF) Printable PDF: one page in Nm and one in ft-lb, with the same estimated rows, plus the method, limitations and sources.
Calculated reference estimates, not installation specifications. T = K × F × d; K = 0.20 (assumed plain, unplated steel); F = 75% of proof stress × tensile stress area; d is in meters. Approximate stress area A = π/4 × (diameter − 0.9382 × pitch)² in mm². Actual friction and joint design can change preload substantially. ISO 898-1 specifies fastener properties, not a universal tightening torque.
Use the equipment or fastener manufacturer’s specified torque and assembly condition. These examples do not cover aluminum threads, fine threads, stainless steel, flange bolts, torque-to-yield fasteners, or safety-critical joints. Do not apply a universal oil, anti-seize, coating or thread-locker reduction.
| Size | Pitch (mm) | Class 8.8 (Nm) | Class 10.9 (Nm) | Class 12.9 (Nm) |
|---|---|---|---|---|
| M4 | 0.7 | 3.1 | 4.4 | 5.1 |
| M5 | 0.8 | 6.2 | 8.8 | 10.3 |
| M6 | 1 | 10.5 | 15 | 17.6 |
| M8 | 1.25 | 25.5 | 36.5 | 42.6 |
| M10 | 1.5 | 50.5 | 72.2 | 84.4 |
| M12 | 1.75 | 88 | 125.9 | 147.1 |
| M14 | 2 | 140.6 | 201.2 | 235.1 |
| M16 | 2 | 218.1 | 312.1 | 364.7 |
| M18 | 2.5 | 311.8 | 431.3 | 504.1 |
| M20 | 2.5 | 440.6 | 609.5 | 712.4 |
| M22 | 2.5 | 600.7 | 831 | 971.2 |
| M24 | 3 | 761.4 | 1053.3 | 1230.9 |
| M27 | 3 | 1116.4 | 1544.3 | 1804.8 |
| M30 | 3.5 | 1513.6 | 2093.8 | 2447 |
| Size | Pitch (mm) | Class 8.8 (ft-lb) | Class 10.9 (ft-lb) | Class 12.9 (ft-lb) |
|---|---|---|---|---|
| M4 | 0.7 | 2.3 | 3.2 | 3.8 |
| M5 | 0.8 | 4.6 | 6.5 | 7.6 |
| M6 | 1 | 7.7 | 11.1 | 13 |
| M8 | 1.25 | 18.8 | 26.9 | 31.4 |
| M10 | 1.5 | 37.2 | 53.2 | 62.2 |
| M12 | 1.75 | 64.9 | 92.9 | 108.5 |
| M14 | 2 | 103.7 | 148.4 | 173.4 |
| M16 | 2 | 160.8 | 230.2 | 269 |
| M18 | 2.5 | 230 | 318.1 | 371.8 |
| M20 | 2.5 | 325 | 449.6 | 525.4 |
| M22 | 2.5 | 443.1 | 612.9 | 716.3 |
| M24 | 3 | 561.6 | 776.9 | 907.9 |
| M27 | 3 | 823.4 | 1139 | 1331.1 |
| M30 | 3.5 | 1116.4 | 1544.3 | 1804.8 |
Calculation references
- Portland Bolt: T = KDP, K = 0.20 for plain unplated bolts and 75% proof-load assumption
- AmesWeb: ISO 898-1:2013 property-class proof stresses (secondary reference)
- AmesWeb: metric stress-area definition and strength limitations
Download the matching calculated metric torque PDF
What is the torque for an M8 bolt?
For M8 × 1.25, this calculation gives 25.5 Nm (18.8 ft-lb) for Class 8.8, 36.5 Nm (26.9 ft-lb) for Class 10.9 and 42.6 Nm (31.4 ft-lb) for Class 12.9, assuming K = 0.20 and 75% of proof load. This is an illustrative estimate, not a manufacturer-approved installation specification. Use the specified torque for your actual joint.
What is the torque for an M10 bolt?
For M10 × 1.5, this calculation gives 50.5 Nm (37.2 ft-lb) for Class 8.8, 72.2 Nm (53.2 ft-lb) for Class 10.9 and 84.4 Nm (62.2 ft-lb) for Class 12.9, assuming K = 0.20 and 75% of proof load. This is an illustrative estimate, not a manufacturer-approved installation specification. Use the specified torque for your actual joint.
What is the torque for an M12 bolt?
For M12 × 1.75, this calculation gives 88 Nm (64.9 ft-lb) for Class 8.8, 125.9 Nm (92.9 ft-lb) for Class 10.9 and 147.1 Nm (108.5 ft-lb) for Class 12.9, assuming K = 0.20 and 75% of proof load. This is an illustrative estimate, not a manufacturer-approved installation specification. Use the specified torque for your actual joint.
What do Class 8.8, 10.9 and 12.9 mean?
They identify mechanical property classes, not universal torque settings. The calculation uses proof stresses of 580 MPa for 8.8 up to M16, 600 MPa above M16, 830 MPa for 10.9 and 970 MPa for 12.9. A higher property class supports a higher proof load, but does not by itself determine the correct assembly torque or make a bolt interchangeable.
Can I reduce these values for oil or anti-seize?
Not by a universal percentage. Oil, anti-seize, plating and thread-lockers have product- and joint-specific friction behavior. Use the manufacturer’s torque and specified assembly condition; the former blanket lubricated toggle has been removed.
Do these estimates apply to fine threads or aluminum?
No. These examples use coarse threads and assume a suitably matched steel nut and adequate engagement. Aluminum thread strength, fine-thread stress area, coatings, flange geometry and torque-to-yield procedures require their own engineering or manufacturer specification.
Tools for torquing metric bolts
As an Amazon Associate WhatSizeBolt earns from qualifying purchases. Tool picks are general options, not a fit guarantee for your vehicle or fastener.
- Torque Wrench (1/2 in., 10–150 ft-lb)Covers M10–M14 values in this chart; check the range includes your figure.EPAuto 1/2" Drive Click Torque Wrench, 10–150 ft-lb — view on Amazon
- Metric Deep Socket Set (10–19 mm, 1/2 in.)Six-point sockets for the M6–M12 hex heads in this chart.pgroup 1/2" Drive Metric Deep Socket Set, 10–19 mm (10 pc) — view on Amazon
- Metric Class 8.8 Bolt AssortmentReplace stretched or damaged bolts rather than re-torquing them.Metric Grade 8.8 Hex Bolt & Nut Assortment, M4–M12 (1,075 pc) — view on Amazon
Related lookups
- Standard SAE & Metric Torque Chart
- Bolt Size Chart (Metric & SAE)
- How to Measure a Bolt
- Thread Pitch Chart
- Bolt Head Markings & Grades
- Torque Converter (in-lb, ft-lb, N-m)
- Find a wrench/socket size
- Vehicle Lookup — Review Field-Level Evidence
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