Bolt Torque Chart
Metric Tightening Torques
Recommended tightening torque values for M6-M36 bolt sizes. Grade 8.8, 10.9, and 12.9. Dry and oiled conditions.
Select Bolt Size
All Torque Values (Dry)
| Bolt Size | Grade 8.8 (Nm) | Grade 10.9 (Nm) | Grade 12.9 (Nm) |
|---|---|---|---|
| M6 | 9.9 | 14.3 | 16.6 |
| M8 | 24 | 34 | 40 |
| M10 | 47 | 67 | 79 |
| M12 | 82 | 117 | 137 |
| M14 | 130 | 186 | 218 |
| M16 | 202 | 289 | 338 |
| M18 | 280 | 400 | 470 |
| M20 | 398 | 569 | 666 |
| M22 | 540 | 773 | 905 |
| M24 | 690 | 987 | 1156 |
| M27 | 1020 | 1460 | 1710 |
| M30 | 1370 | 1960 | 2300 |
| M33 | 1870 | 2670 | 3130 |
| M36 | 2400 | 3430 | 4020 |
* Values apply to standard metric bolts (ISO 898). Click a row to see details.
Technical Notes
- 1.Grade 8.8: General purpose high-strength bolt. Min. tensile strength 800 MPa.
- 2.Grade 10.9: High performance applications. Min. tensile strength 1000 MPa.
- 3.Grade 12.9: Highest strength class. Min. tensile strength 1200 MPa.
- 4.In oiled condition (K=0.12), torque values are approximately 75% of dry (K=0.16) values.
- 5.Flange connections should use cross-pattern (star) tightening method.
Flange & Fastener Supply
As Aktif Celik, we supply Grade 8.8, 10.9, and 12.9 bolts and flange fasteners.
Get a QuoteHow are bolt torque values determined?
Bolt tightening torque depends on the bolt diameter, property class (8.8 / 10.9 / 12.9) and friction. Typical values for class 8.8, dry: M6 ≈ 10 Nm, M8 ≈ 25 Nm, M10 ≈ 49 Nm, M12 ≈ 85 Nm, M16 ≈ 210 Nm, M20 ≈ 410 Nm. Class 10.9 is about 1.4× these values.
Torque, preload and friction
Tightening torque is applied to create a controlled preload (clamp load) in the bolt; most of the torque is actually spent overcoming thread and under-head friction. Lubrication therefore changes the torque–preload relationship: for the same preload, a lubricated joint needs ~15–25% less torque. The values apply to ISO 898-1 property classes and metric ISO threads; for critical joints, always use the manufacturer or standard table.
Common bolt torque values (Grade 8.8, dry)
| Bolt size | Thread pitch (mm) | Torque (Nm) | Torque (ft-lbs) |
|---|---|---|---|
| M6 | 1.0 | 10 | 7.4 |
| M8 | 1.25 | 25 | 18.4 |
| M10 | 1.5 | 49 | 36.1 |
| M12 | 1.75 | 85 | 62.7 |
| M14 | 2.0 | 135 | 99.6 |
| M16 | 2.0 | 210 | 155 |
| M18 | 2.5 | 294 | 217 |
| M20 | 2.5 | 410 | 302 |
| M22 | 2.5 | 555 | 409 |
| M24 | 3.0 | 710 | 524 |
| M27 | 3.0 | 1050 | 774 |
| M30 | 3.5 | 1450 | 1070 |
Values for ISO 898-1 Grade 8.8, metric coarse thread, dry friction (K approx 0.20). Lubricated joints require approximately 30% less torque for the same preload. For Grade 10.9 multiply by 1.4; for Grade 12.9 multiply by 1.65.
Frequently Asked Questions
What is the torque for an M10 8.8 bolt?+
About 48–49 Nm dry. A lubricated joint requires less.
What is the torque difference between class 8.8 and 10.9?+
Class 10.9 has a higher yield strength; for the same diameter its torque is ~1.4× that of 8.8, and 12.9 is ~1.65×.
Why is torque different for lubricated vs dry bolts?+
Lubrication lowers the friction coefficient, so the same preload needs ~15–25% less torque. Assuming dry when lubricated over-tightens the bolt.
How do you calculate bolt torque?+
T = K × d × F (K friction factor ≈0.2 dry; d diameter; F preload). In practice a torque chart is used.
What torque for an M20 bolt?+
Dry M20: ≈410 Nm for class 8.8, ≈490 Nm for 10.9, ≈580 Nm for 12.9. Lubricated joints need 15–25% less torque for the same preload.
Why does dry vs lubricated matter?+
Lubrication lowers friction; applying the dry value to a lubricated bolt over-tightens it and can take it past yield.
What is the difference between dry and lubricated bolt torque?+
Lubricated bolts require approximately 30% less torque to achieve the same clamping force because the friction coefficient drops from ~0.20 (dry) to ~0.12–0.15 (lubricated).
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