M14 Bolt Torque
An M14 8.8 bolt with a coarse M14×2 thread needs about 141.8 N·m (104.6 ft·lb) when dry and 106.2 N·m (78.3 ft·lb) when oiled, tightened to 70% of yield (clamp force 51.7 kN).
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 19.4 kN4360 lbf | 53.2 N·m39.2 ft·lb | 39.8 N·m29.4 ft·lb | 26.5 N·m19.5 ft·lb |
| 4.8 | 25.9 kN5813 lbf | 70.9 N·m52.3 ft·lb | 53.1 N·m39.2 ft·lb | 35.3 N·m26.0 ft·lb |
| 5.6 | 24.2 kN5450 lbf | 66.5 N·m49.0 ft·lb | 49.8 N·m36.7 ft·lb | 33.1 N·m24.4 ft·lb |
| 5.8 | 32.3 kN7266 lbf | 88.6 N·m65.4 ft·lb | 66.4 N·m49.0 ft·lb | 44.1 N·m32.6 ft·lb |
| 6.8 | 38.8 kN8720 lbf | 106.3 N·m78.4 ft·lb | 79.7 N·m58.8 ft·lb | 53.0 N·m39.1 ft·lb |
| 8.8 | 51.7 kN11626 lbf | 141.8 N·m104.6 ft·lb | 106.2 N·m78.3 ft·lb | 70.6 N·m52.1 ft·lb |
| 9.8 | 58.2 kN13080 lbf | 159.5 N·m117.7 ft·lb | 119.5 N·m88.1 ft·lb | 79.5 N·m58.6 ft·lb |
| 10.9 | 72.7 kN16350 lbf | 199.4 N·m147.1 ft·lb | 149.4 N·m110.2 ft·lb | 99.3 N·m73.3 ft·lb |
| 12.9 | 87.3 kN19620 lbf | 239.3 N·m176.5 ft·lb | 179.2 N·m132.2 ft·lb | 119.2 N·m87.9 ft·lb |
| A2-70 | 36.4 kN8175 lbf | 99.7 N·m73.5 ft·lb | 74.7 N·m55.1 ft·lb | 49.7 N·m36.6 ft·lb |
| A4-70 | 36.4 kN8175 lbf | 99.7 N·m73.5 ft·lb | 74.7 N·m55.1 ft·lb | 49.7 N·m36.6 ft·lb |
| A4-80 | 48.5 kN10900 lbf | 132.9 N·m98.0 ft·lb | 99.6 N·m73.4 ft·lb | 66.2 N·m48.8 ft·lb |
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 20.9 kN4704 lbf | 56.3 N·m41.5 ft·lb | 41.7 N·m30.8 ft·lb | 27.2 N·m20.0 ft·lb |
| 4.8 | 27.9 kN6272 lbf | 75.0 N·m55.3 ft·lb | 55.6 N·m41.0 ft·lb | 36.2 N·m26.7 ft·lb |
| 5.6 | 26.2 kN5880 lbf | 70.3 N·m51.9 ft·lb | 52.1 N·m38.5 ft·lb | 33.9 N·m25.0 ft·lb |
| 5.8 | 34.9 kN7840 lbf | 93.8 N·m69.2 ft·lb | 69.5 N·m51.3 ft·lb | 45.3 N·m33.4 ft·lb |
| 6.8 | 41.8 kN9408 lbf | 112.5 N·m83.0 ft·lb | 83.4 N·m61.5 ft·lb | 54.3 N·m40.1 ft·lb |
| 8.8 | 55.8 kN12544 lbf | 150.1 N·m110.7 ft·lb | 111.2 N·m82.0 ft·lb | 72.4 N·m53.4 ft·lb |
| 9.8 | 62.8 kN14111 lbf | 168.8 N·m124.5 ft·lb | 125.1 N·m92.3 ft·lb | 81.5 N·m60.1 ft·lb |
| 10.9 | 78.5 kN17639 lbf | 211.0 N·m155.6 ft·lb | 156.4 N·m115.4 ft·lb | 101.8 N·m75.1 ft·lb |
| 12.9 | 94.2 kN21167 lbf | 253.2 N·m186.8 ft·lb | 187.7 N·m138.4 ft·lb | 122.2 N·m90.1 ft·lb |
| A2-70 | 39.2 kN8820 lbf | 105.5 N·m77.8 ft·lb | 78.2 N·m57.7 ft·lb | 50.9 N·m37.6 ft·lb |
| A4-70 | 39.2 kN8820 lbf | 105.5 N·m77.8 ft·lb | 78.2 N·m57.7 ft·lb | 50.9 N·m37.6 ft·lb |
| A4-80 | 52.3 kN11760 lbf | 140.7 N·m103.8 ft·lb | 104.3 N·m76.9 ft·lb | 67.9 N·m50.1 ft·lb |
Torque for M14 hex head bolts and nuts, standard ISO/ASME heads on steel with a 15.5 mm clearance hole. Friction μ applies to both the threads and the bearing face. Always follow the manufacturer's value where one exists.
M14 thread and dimensions
- Coarse thread
- M14×2 — pitch 2 mm
- Fine thread
- M14×1.5 — pitch 1.5 mm
- Tensile stress area Aₛ
- 115.4 mm² (coarse), 124.5 mm² (fine)
- Pitch diameter d₂
- 12.701 mm
- Tap drill
- 12 mm (coarse), 12.5 mm (fine)
- Wrench size (hex head)
- 21 mm (DIN: 22 mm)
- Clearance hole
- 15.5 mm
How the M14 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 × 115.4 mm² = 51.7 kN
T = F × (0.16·P + 0.58·μ·d₂ + μ·Dₖₘ/2)
T = 51.7 kN × (0.16·2 + 0.58·0.15·12.70 + 0.15·18.25/2) mm = 141.8 N·m
Here d₂ is the pitch diameter and Dₖₘ the effective bearing diameter of the head (18.25 mm). Change the grade, lubrication or preload in the calculator below.
Frequently asked questions
What is the torque for an M14 8.8 bolt?
About 141.8 N·m (104.6 ft·lb) with dry threads, 106.2 N·m (78.3 ft·lb) with oiled threads and 70.6 N·m (52.1 ft·lb) with PTFE or moly paste, for a coarse M14×2 thread tightened to 70% of yield. The resulting clamp force is 51.7 kN.
What is the torque for an M14 10.9 bolt?
About 199.4 N·m (147.1 ft·lb) with dry threads, 149.4 N·m (110.2 ft·lb) with oiled threads and 99.3 N·m (73.3 ft·lb) with PTFE or moly paste, for a coarse M14×2 thread tightened to 70% of yield. The resulting clamp force is 72.7 kN.
What size wrench fits an M14 bolt?
A standard M14 hex head bolt or nut takes a 21 mm (DIN: 22 mm) wrench or socket.
What drill size do I need to tap M14?
Use a 12 mm drill for M14×2 and 12.5 mm for M14×1.5.