M64 Bolt Torque
An M64 8.8 bolt with a coarse M64×6 thread needs about 14550.0 N·m (10731.5 ft·lb) when dry and 10743.4 N·m (7924.0 ft·lb) when oiled, tightened to 70% of yield (clamp force 1198.8 kN).
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 449.6 kN101066 lbf | 5456.3 N·m4024.3 ft·lb | 4028.8 N·m2971.5 ft·lb | 2601.3 N·m1918.6 ft·lb |
| 4.8 | 599.4 kN134754 lbf | 7275.0 N·m5365.8 ft·lb | 5371.7 N·m3962.0 ft·lb | 3468.4 N·m2558.2 ft·lb |
| 5.6 | 562.0 kN126332 lbf | 6820.3 N·m5030.4 ft·lb | 5036.0 N·m3714.4 ft·lb | 3251.7 N·m2398.3 ft·lb |
| 5.8 | 749.3 kN168443 lbf | 9093.8 N·m6707.2 ft·lb | 6714.6 N·m4952.5 ft·lb | 4335.5 N·m3197.7 ft·lb |
| 6.8 | 899.1 kN202132 lbf | 10912.5 N·m8048.6 ft·lb | 8057.6 N·m5943.0 ft·lb | 5202.6 N·m3837.3 ft·lb |
| 8.8 | 1198.8 kN269509 lbf | 14550.0 N·m10731.5 ft·lb | 10743.4 N·m7924.0 ft·lb | 6936.9 N·m5116.4 ft·lb |
| 10.9 | 1685.9 kN378997 lbf | 20460.9 N·m15091.2 ft·lb | 15108.0 N·m11143.1 ft·lb | 9755.0 N·m7194.9 ft·lb |
| 12.9 | 2023.0 kN454796 lbf | 24553.1 N·m18109.5 ft·lb | 18129.5 N·m13371.7 ft·lb | 11706.0 N·m8633.9 ft·lb |
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 478.9 kN107668 lbf | 5712.4 N·m4213.3 ft·lb | 4176.6 N·m3080.5 ft·lb | 2640.9 N·m1947.8 ft·lb |
| 4.8 | 638.6 kN143557 lbf | 7616.6 N·m5617.7 ft·lb | 5568.9 N·m4107.4 ft·lb | 3521.2 N·m2597.1 ft·lb |
| 5.6 | 598.7 kN134585 lbf | 7140.5 N·m5266.6 ft·lb | 5220.8 N·m3850.7 ft·lb | 3301.1 N·m2434.8 ft·lb |
| 5.8 | 798.2 kN179447 lbf | 9520.7 N·m7022.1 ft·lb | 6961.1 N·m5134.2 ft·lb | 4401.5 N·m3246.4 ft·lb |
| 6.8 | 957.9 kN215336 lbf | 11424.8 N·m8426.5 ft·lb | 8353.3 N·m6161.1 ft·lb | 5281.8 N·m3895.6 ft·lb |
| 8.8 | 1277.1 kN287115 lbf | 15233.1 N·m11235.4 ft·lb | 11137.7 N·m8214.8 ft·lb | 7042.4 N·m5194.2 ft·lb |
| 10.9 | 1796.0 kN403755 lbf | 21421.6 N·m15799.7 ft·lb | 15662.4 N·m11552.0 ft·lb | 9903.3 N·m7304.3 ft·lb |
| 12.9 | 2155.2 kN484506 lbf | 25705.9 N·m18959.7 ft·lb | 18794.9 N·m13862.4 ft·lb | 11884.0 N·m8765.2 ft·lb |
Torque for M64 hex head bolts and nuts, standard ISO/ASME heads on steel with a 70.0 mm clearance hole. Friction μ applies to both the threads and the bearing face. Always follow the manufacturer's value where one exists.
M64 thread and dimensions
- Coarse thread
- M64×6 — pitch 6 mm
- Fine thread
- M64×4 — pitch 4 mm
- Tensile stress area Aₛ
- 2676.0 mm² (coarse), 2850.8 mm² (fine)
- Pitch diameter d₂
- 60.103 mm
- Tap drill
- 58 mm (coarse), 60 mm (fine)
- Wrench size (hex head)
- 95 mm
- Clearance hole
- 70.0 mm
How the M64 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 × 2676.0 mm² = 1198.8 kN
T = F × (0.16·P + 0.58·μ·d₂ + μ·Dₖₘ/2)
T = 1198.8 kN × (0.16·6 + 0.58·0.15·60.10 + 0.15·82.50/2) mm = 14550.0 N·m
Here d₂ is the pitch diameter and Dₖₘ the effective bearing diameter of the head (82.50 mm). Change the grade, lubrication or preload in the calculator below.
Frequently asked questions
What is the torque for an M64 8.8 bolt?
About 14550.0 N·m (10731.5 ft·lb) with dry threads, 10743.4 N·m (7924.0 ft·lb) with oiled threads and 6936.9 N·m (5116.4 ft·lb) with PTFE or moly paste, for a coarse M64×6 thread tightened to 70% of yield. The resulting clamp force is 1198.8 kN.
What is the torque for an M64 10.9 bolt?
About 20460.9 N·m (15091.2 ft·lb) with dry threads, 15108.0 N·m (11143.1 ft·lb) with oiled threads and 9755.0 N·m (7194.9 ft·lb) with PTFE or moly paste, for a coarse M64×6 thread tightened to 70% of yield. The resulting clamp force is 1685.9 kN.
What size wrench fits an M64 bolt?
A standard M64 hex head bolt or nut takes a 95 mm wrench or socket.
What drill size do I need to tap M64?
Use a 58 mm drill for M64×6 and 60 mm for M64×4.