M16 Bolt Torque
An M16 8.8 bolt with a coarse M16×2 thread needs about 217.3 N·m (160.3 ft·lb) when dry and 161.9 N·m (119.4 ft·lb) when oiled, tightened to 70% of yield (clamp force 70.2 kN).
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 26.3 kN5917 lbf | 81.5 N·m60.1 ft·lb | 60.7 N·m44.8 ft·lb | 40.0 N·m29.5 ft·lb |
| 4.8 | 35.1 kN7889 lbf | 108.6 N·m80.1 ft·lb | 81.0 N·m59.7 ft·lb | 53.3 N·m39.3 ft·lb |
| 5.6 | 32.9 kN7396 lbf | 101.9 N·m75.1 ft·lb | 75.9 N·m56.0 ft·lb | 50.0 N·m36.9 ft·lb |
| 5.8 | 43.9 kN9862 lbf | 135.8 N·m100.2 ft·lb | 101.2 N·m74.6 ft·lb | 66.6 N·m49.1 ft·lb |
| 6.8 | 52.6 kN11834 lbf | 163.0 N·m120.2 ft·lb | 121.5 N·m89.6 ft·lb | 79.9 N·m59.0 ft·lb |
| 8.8 | 70.2 kN15779 lbf | 217.3 N·m160.3 ft·lb | 161.9 N·m119.4 ft·lb | 106.6 N·m78.6 ft·lb |
| 9.8 | 79.0 kN17751 lbf | 244.4 N·m180.3 ft·lb | 182.2 N·m134.4 ft·lb | 119.9 N·m88.4 ft·lb |
| 10.9 | 98.7 kN22189 lbf | 305.6 N·m225.4 ft·lb | 227.7 N·m168.0 ft·lb | 149.9 N·m110.6 ft·lb |
| 12.9 | 118.4 kN26627 lbf | 366.7 N·m270.4 ft·lb | 273.3 N·m201.5 ft·lb | 179.9 N·m132.7 ft·lb |
| A2-70 | 49.4 kN11094 lbf | 152.8 N·m112.7 ft·lb | 113.9 N·m84.0 ft·lb | 74.9 N·m55.3 ft·lb |
| A4-70 | 49.4 kN11094 lbf | 152.8 N·m112.7 ft·lb | 113.9 N·m84.0 ft·lb | 74.9 N·m55.3 ft·lb |
| A4-80 | 65.8 kN14793 lbf | 203.7 N·m150.2 ft·lb | 151.8 N·m112.0 ft·lb | 99.9 N·m73.7 ft·lb |
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 28.1 kN6317 lbf | 85.5 N·m63.1 ft·lb | 63.1 N·m46.6 ft·lb | 40.8 N·m30.1 ft·lb |
| 4.8 | 37.5 kN8422 lbf | 114.0 N·m84.1 ft·lb | 84.2 N·m62.1 ft·lb | 54.3 N·m40.1 ft·lb |
| 5.6 | 35.1 kN7896 lbf | 106.9 N·m78.8 ft·lb | 78.9 N·m58.2 ft·lb | 50.9 N·m37.6 ft·lb |
| 5.8 | 46.8 kN10528 lbf | 142.5 N·m105.1 ft·lb | 105.2 N·m77.6 ft·lb | 67.9 N·m50.1 ft·lb |
| 6.8 | 56.2 kN12633 lbf | 171.0 N·m126.1 ft·lb | 126.3 N·m93.1 ft·lb | 81.5 N·m60.1 ft·lb |
| 8.8 | 74.9 kN16844 lbf | 228.0 N·m168.2 ft·lb | 168.4 N·m124.2 ft·lb | 108.7 N·m80.2 ft·lb |
| 9.8 | 84.3 kN18950 lbf | 256.5 N·m189.2 ft·lb | 189.4 N·m139.7 ft·lb | 122.3 N·m90.2 ft·lb |
| 10.9 | 105.4 kN23687 lbf | 320.7 N·m236.5 ft·lb | 236.8 N·m174.6 ft·lb | 152.8 N·m112.7 ft·lb |
| 12.9 | 126.4 kN28425 lbf | 384.8 N·m283.8 ft·lb | 284.1 N·m209.5 ft·lb | 183.4 N·m135.3 ft·lb |
| A2-70 | 52.7 kN11844 lbf | 160.3 N·m118.3 ft·lb | 118.4 N·m87.3 ft·lb | 76.4 N·m56.4 ft·lb |
| A4-70 | 52.7 kN11844 lbf | 160.3 N·m118.3 ft·lb | 118.4 N·m87.3 ft·lb | 76.4 N·m56.4 ft·lb |
| A4-80 | 70.2 kN15792 lbf | 213.8 N·m157.7 ft·lb | 157.8 N·m116.4 ft·lb | 101.9 N·m75.2 ft·lb |
Torque for M16 hex head bolts and nuts, standard ISO/ASME heads on steel with a 17.5 mm clearance hole. Friction μ applies to both the threads and the bearing face. Always follow the manufacturer's value where one exists.
M16 thread and dimensions
- Coarse thread
- M16×2 — pitch 2 mm
- Fine thread
- M16×1.5 — pitch 1.5 mm
- Tensile stress area Aₛ
- 156.7 mm² (coarse), 167.2 mm² (fine)
- Pitch diameter d₂
- 14.701 mm
- Tap drill
- 14 mm (coarse), 14.5 mm (fine)
- Wrench size (hex head)
- 24 mm
- Clearance hole
- 17.5 mm
How the M16 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 × 156.7 mm² = 70.2 kN
T = F × (0.16·P + 0.58·μ·d₂ + μ·Dₖₘ/2)
T = 70.2 kN × (0.16·2 + 0.58·0.15·14.70 + 0.15·20.75/2) mm = 217.3 N·m
Here d₂ is the pitch diameter and Dₖₘ the effective bearing diameter of the head (20.75 mm). Change the grade, lubrication or preload in the calculator below.
Frequently asked questions
What is the torque for an M16 8.8 bolt?
About 217.3 N·m (160.3 ft·lb) with dry threads, 161.9 N·m (119.4 ft·lb) with oiled threads and 106.6 N·m (78.6 ft·lb) with PTFE or moly paste, for a coarse M16×2 thread tightened to 70% of yield. The resulting clamp force is 70.2 kN.
What is the torque for an M16 10.9 bolt?
About 305.6 N·m (225.4 ft·lb) with dry threads, 227.7 N·m (168.0 ft·lb) with oiled threads and 149.9 N·m (110.6 ft·lb) with PTFE or moly paste, for a coarse M16×2 thread tightened to 70% of yield. The resulting clamp force is 98.7 kN.
What size wrench fits an M16 bolt?
A standard M16 hex head bolt or nut takes a 24 mm wrench or socket.
What drill size do I need to tap M16?
Use a 14 mm drill for M16×2 and 14.5 mm for M16×1.5.