M6 Bolt Torque
An M6 8.8 bolt with a coarse M6×1 thread needs about 11.0 N·m (8.15 ft·lb) when dry and 8.32 N·m (6.13 ft·lb) when oiled, tightened to 70% of yield (clamp force 9.02 kN).
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 3.38 kN760 lbf | 4.14 N·m3.05 ft·lb | 3.12 N·m2.30 ft·lb | 2.10 N·m1.55 ft·lb |
| 4.8 | 4.51 kN1013 lbf | 5.52 N·m4.07 ft·lb | 4.16 N·m3.07 ft·lb | 2.79 N·m2.06 ft·lb |
| 5.6 | 4.23 kN950 lbf | 5.18 N·m3.82 ft·lb | 3.90 N·m2.88 ft·lb | 2.62 N·m1.93 ft·lb |
| 5.8 | 5.63 kN1267 lbf | 6.90 N·m5.09 ft·lb | 5.20 N·m3.83 ft·lb | 3.49 N·m2.58 ft·lb |
| 6.8 | 6.76 kN1520 lbf | 8.28 N·m6.11 ft·lb | 6.24 N·m4.60 ft·lb | 4.19 N·m3.09 ft·lb |
| 8.8 | 9.02 kN2027 lbf | 11.0 N·m8.15 ft·lb | 8.32 N·m6.13 ft·lb | 5.59 N·m4.12 ft·lb |
| 9.8 | 10.1 kN2280 lbf | 12.4 N·m9.16 ft·lb | 9.36 N·m6.90 ft·lb | 6.29 N·m4.64 ft·lb |
| 10.9 | 12.7 kN2850 lbf | 15.5 N·m11.5 ft·lb | 11.7 N·m8.63 ft·lb | 7.86 N·m5.80 ft·lb |
| 12.9 | 15.2 kN3420 lbf | 18.6 N·m13.7 ft·lb | 14.0 N·m10.4 ft·lb | 9.43 N·m6.96 ft·lb |
| A2-70 | 6.34 kN1425 lbf | 7.77 N·m5.73 ft·lb | 5.85 N·m4.31 ft·lb | 3.93 N·m2.90 ft·lb |
| A4-70 | 6.34 kN1425 lbf | 7.77 N·m5.73 ft·lb | 5.85 N·m4.31 ft·lb | 3.93 N·m2.90 ft·lb |
| A4-80 | 8.45 kN1900 lbf | 10.4 N·m7.64 ft·lb | 7.80 N·m5.75 ft·lb | 5.24 N·m3.86 ft·lb |
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 3.70 kN832 lbf | 4.44 N·m3.27 ft·lb | 3.30 N·m2.44 ft·lb | 2.17 N·m1.60 ft·lb |
| 4.8 | 4.94 kN1109 lbf | 5.92 N·m4.36 ft·lb | 4.40 N·m3.25 ft·lb | 2.89 N·m2.13 ft·lb |
| 5.6 | 4.63 kN1040 lbf | 5.55 N·m4.09 ft·lb | 4.13 N·m3.05 ft·lb | 2.71 N·m2.00 ft·lb |
| 5.8 | 6.17 kN1387 lbf | 7.40 N·m5.46 ft·lb | 5.51 N·m4.06 ft·lb | 3.61 N·m2.67 ft·lb |
| 6.8 | 7.40 kN1664 lbf | 8.88 N·m6.55 ft·lb | 6.61 N·m4.87 ft·lb | 4.34 N·m3.20 ft·lb |
| 8.8 | 9.87 kN2219 lbf | 11.8 N·m8.73 ft·lb | 8.81 N·m6.50 ft·lb | 5.78 N·m4.27 ft·lb |
| 9.8 | 11.1 kN2496 lbf | 13.3 N·m9.82 ft·lb | 9.91 N·m7.31 ft·lb | 6.51 N·m4.80 ft·lb |
| 10.9 | 13.9 kN3120 lbf | 16.6 N·m12.3 ft·lb | 12.4 N·m9.14 ft·lb | 8.13 N·m6.00 ft·lb |
| 12.9 | 16.7 kN3744 lbf | 20.0 N·m14.7 ft·lb | 14.9 N·m11.0 ft·lb | 9.76 N·m7.20 ft·lb |
| A2-70 | 6.94 kN1560 lbf | 8.32 N·m6.14 ft·lb | 6.19 N·m4.57 ft·lb | 4.07 N·m3.00 ft·lb |
| A4-70 | 6.94 kN1560 lbf | 8.32 N·m6.14 ft·lb | 6.19 N·m4.57 ft·lb | 4.07 N·m3.00 ft·lb |
| A4-80 | 9.25 kN2080 lbf | 11.1 N·m8.18 ft·lb | 8.26 N·m6.09 ft·lb | 5.42 N·m4.00 ft·lb |
Torque for M6 hex head bolts and nuts, standard ISO/ASME heads on steel with a 6.6 mm clearance hole. Friction μ applies to both the threads and the bearing face. Always follow the manufacturer's value where one exists.
M6 thread and dimensions
- Coarse thread
- M6×1 — pitch 1 mm
- Fine thread
- M6×0.75 — pitch 0.75 mm
- Tensile stress area Aₛ
- 20.1 mm² (coarse), 22.0 mm² (fine)
- Pitch diameter d₂
- 5.351 mm
- Tap drill
- 5 mm (coarse), 5.25 mm (fine)
- Wrench size (hex head)
- 10 mm
- Clearance hole
- 6.6 mm
How the M6 torque is calculated
Preload is 70% of the bolt's yield strength times its tensile stress area. Torque then follows the ISO 16047 / VDI 2230 formula, which splits it into thread pitch, thread friction and friction under the head:
F = 70% × 640 MPa × 20.1 mm² = 9.02 kN
T = F × (0.16·P + 0.58·μ·d₂ + μ·Dₖₘ/2)
T = 9.02 kN × (0.16·1 + 0.58·0.15·5.35 + 0.15·8.30/2) mm = 11.0 N·m
Here d₂ is the pitch diameter and Dₖₘ the effective bearing diameter of the head (8.30 mm). Change the grade, lubrication or preload in the calculator below.
Frequently asked questions
What is the torque for an M6 8.8 bolt?
About 11.0 N·m (8.15 ft·lb) with dry threads, 8.32 N·m (6.13 ft·lb) with oiled threads and 5.59 N·m (4.12 ft·lb) with PTFE or moly paste, for a coarse M6×1 thread tightened to 70% of yield. The resulting clamp force is 9.02 kN.
What is the torque for an M6 10.9 bolt?
About 15.5 N·m (11.5 ft·lb) with dry threads, 11.7 N·m (8.63 ft·lb) with oiled threads and 7.86 N·m (5.80 ft·lb) with PTFE or moly paste, for a coarse M6×1 thread tightened to 70% of yield. The resulting clamp force is 12.7 kN.
What size wrench fits an M6 bolt?
A standard M6 hex head bolt or nut takes a 10 mm wrench or socket.
What drill size do I need to tap M6?
Use a 5 mm drill for M6×1 and 5.25 mm for M6×0.75.