Bolt Torque Lookup
General torque ranges for common bolt sizes and grades -- always confirm the actual spec for critical fasteners.
| Bolt size / grade | Torque range |
|---|---|
| 1/4-20 (Grade 5) | 8–10 ft-lb |
| 5/16-18 (Grade 5) | 15–17 ft-lb |
| 3/8-16 (Grade 5) | 30–35 ft-lb |
| 7/16-14 (Grade 5) | 45–50 ft-lb |
| 1/2-13 (Grade 5) | 65–75 ft-lb |
| M6 (8.8) | 9–10 Nm |
| M8 (8.8) | 22–25 Nm |
| M10 (8.8) | 45–50 Nm |
| M12 (8.8) | 80–90 Nm |
General reference only -- not a substitute for the real spec
These ranges assume clean, dry threads and standard steel-to-steel joints at the listed grade. Real specs vary by application, thread lubrication (a lubricated bolt often needs less torque than a dry one for the same clamping force), and the specific material being joined -- always use the manufacturer's actual torque spec for critical fasteners like engine, suspension, or safety-related hardware.
Where these numbers come from
General published torque ranges for common Grade 5 (SAE) and Class 8.8 (metric) fasteners under dry, standard conditions. Use the exact specification from your vehicle or component's service manual for anything structurally or safety-critical -- these ranges are a general reference, not a substitute.
Frequently asked questions
Why does thread lubrication change the torque needed?
A lubricated (or plated) bolt has less friction, so it reaches the same actual clamping force at a lower torque reading than a dry bolt would -- using a dry spec on a lubricated bolt can over-tighten it.
What's the difference between Grade 5 and Grade 8 bolts?
Grade 8 bolts are made from stronger steel and can be torqued higher than Grade 5 of the same size -- always match the torque spec to the actual bolt grade, identifiable by the markings on the bolt head.
Should I always use the maximum torque in a range?
Not necessarily -- match the specific application's actual spec when available; these ranges are a general starting reference for when no exact spec is at hand.
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