M3.5 Bolt Torque
An M3.5 8.8 bolt with a coarse M3.5×0.6 thread needs about 2.20 N·m (1.62 ft·lb) when dry and 1.66 N·m (1.22 ft·lb) when oiled, tightened to 70% of yield (clamp force 3.04 kN).
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 1.14 kN256 lbf | 0.82 N·m0.61 ft·lb | 0.62 N·m0.46 ft·lb | 0.42 N·m0.31 ft·lb |
| 4.8 | 1.52 kN341 lbf | 1.10 N·m0.81 ft·lb | 0.83 N·m0.61 ft·lb | 0.56 N·m0.41 ft·lb |
| 5.6 | 1.42 kN320 lbf | 1.03 N·m0.76 ft·lb | 0.78 N·m0.57 ft·lb | 0.52 N·m0.39 ft·lb |
| 5.8 | 1.90 kN426 lbf | 1.37 N·m1.01 ft·lb | 1.04 N·m0.76 ft·lb | 0.70 N·m0.51 ft·lb |
| 6.8 | 2.28 kN512 lbf | 1.65 N·m1.22 ft·lb | 1.24 N·m0.92 ft·lb | 0.84 N·m0.62 ft·lb |
| 8.8 | 3.04 kN682 lbf | 2.20 N·m1.62 ft·lb | 1.66 N·m1.22 ft·lb | 1.11 N·m0.82 ft·lb |
| 9.8 | 3.41 kN768 lbf | 2.47 N·m1.82 ft·lb | 1.86 N·m1.37 ft·lb | 1.25 N·m0.93 ft·lb |
| 10.9 | 4.27 kN960 lbf | 3.09 N·m2.28 ft·lb | 2.33 N·m1.72 ft·lb | 1.57 N·m1.16 ft·lb |
| 12.9 | 5.12 kN1151 lbf | 3.71 N·m2.74 ft·lb | 2.80 N·m2.06 ft·lb | 1.88 N·m1.39 ft·lb |
| A2-70 | 2.13 kN480 lbf | 1.55 N·m1.14 ft·lb | 1.16 N·m0.86 ft·lb | 0.78 N·m0.58 ft·lb |
| A4-70 | 2.13 kN480 lbf | 1.55 N·m1.14 ft·lb | 1.16 N·m0.86 ft·lb | 0.78 N·m0.58 ft·lb |
| A4-80 | 2.85 kN640 lbf | 2.06 N·m1.52 ft·lb | 1.55 N·m1.15 ft·lb | 1.05 N·m0.77 ft·lb |
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 1.33 kN298 lbf | 0.93 N·m0.68 ft·lb | 0.68 N·m0.50 ft·lb | 0.44 N·m0.33 ft·lb |
| 4.8 | 1.77 kN398 lbf | 1.24 N·m0.91 ft·lb | 0.91 N·m0.67 ft·lb | 0.59 N·m0.44 ft·lb |
| 5.6 | 1.66 kN373 lbf | 1.16 N·m0.85 ft·lb | 0.86 N·m0.63 ft·lb | 0.55 N·m0.41 ft·lb |
| 5.8 | 2.21 kN497 lbf | 1.54 N·m1.14 ft·lb | 1.14 N·m0.84 ft·lb | 0.74 N·m0.54 ft·lb |
| 6.8 | 2.65 kN597 lbf | 1.85 N·m1.37 ft·lb | 1.37 N·m1.01 ft·lb | 0.88 N·m0.65 ft·lb |
| 8.8 | 3.54 kN796 lbf | 2.47 N·m1.82 ft·lb | 1.83 N·m1.35 ft·lb | 1.18 N·m0.87 ft·lb |
| 9.8 | 3.98 kN895 lbf | 2.78 N·m2.05 ft·lb | 2.05 N·m1.51 ft·lb | 1.33 N·m0.98 ft·lb |
| 10.9 | 4.98 kN1119 lbf | 3.48 N·m2.56 ft·lb | 2.57 N·m1.89 ft·lb | 1.66 N·m1.22 ft·lb |
| 12.9 | 5.97 kN1343 lbf | 4.17 N·m3.08 ft·lb | 3.08 N·m2.27 ft·lb | 1.99 N·m1.47 ft·lb |
| A2-70 | 2.49 kN559 lbf | 1.74 N·m1.28 ft·lb | 1.28 N·m0.95 ft·lb | 0.83 N·m0.61 ft·lb |
| A4-70 | 2.49 kN559 lbf | 1.74 N·m1.28 ft·lb | 1.28 N·m0.95 ft·lb | 0.83 N·m0.61 ft·lb |
| A4-80 | 3.32 kN746 lbf | 2.32 N·m1.71 ft·lb | 1.71 N·m1.26 ft·lb | 1.11 N·m0.82 ft·lb |
Torque for M3.5 hex head bolts and nuts, standard ISO/ASME heads on steel with a 3.9 mm clearance hole. Friction μ applies to both the threads and the bearing face. Always follow the manufacturer's value where one exists.
M3.5 thread and dimensions
- Coarse thread
- M3.5×0.6 — pitch 0.6 mm
- Fine thread
- M3.5×0.35 — pitch 0.35 mm
- Tensile stress area Aₛ
- 6.78 mm² (coarse), 7.90 mm² (fine)
- Pitch diameter d₂
- 3.110 mm
- Tap drill
- 2.9 mm (coarse), 3.15 mm (fine)
- Wrench size (hex head)
- 6 mm
- Clearance hole
- 3.9 mm
How the M3.5 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 × 6.78 mm² = 3.04 kN
T = F × (0.16·P + 0.58·μ·d₂ + μ·Dₖₘ/2)
T = 3.04 kN × (0.16·0.6 + 0.58·0.15·3.11 + 0.15·4.95/2) mm = 2.20 N·m
Here d₂ is the pitch diameter and Dₖₘ the effective bearing diameter of the head (4.95 mm). Change the grade, lubrication or preload in the calculator below.
Frequently asked questions
What is the torque for an M3.5 8.8 bolt?
About 2.20 N·m (1.62 ft·lb) with dry threads, 1.66 N·m (1.22 ft·lb) with oiled threads and 1.11 N·m (0.82 ft·lb) with PTFE or moly paste, for a coarse M3.5×0.6 thread tightened to 70% of yield. The resulting clamp force is 3.04 kN.
What is the torque for an M3.5 10.9 bolt?
About 3.09 N·m (2.28 ft·lb) with dry threads, 2.33 N·m (1.72 ft·lb) with oiled threads and 1.57 N·m (1.16 ft·lb) with PTFE or moly paste, for a coarse M3.5×0.6 thread tightened to 70% of yield. The resulting clamp force is 4.27 kN.
What size wrench fits an M3.5 bolt?
A standard M3.5 hex head bolt or nut takes a 6 mm wrench or socket.
What drill size do I need to tap M3.5?
Use a 2.9 mm drill for M3.5×0.6 and 3.15 mm for M3.5×0.35.