M24 Bolt Torque
An M24 8.8 bolt with a coarse M24×3 thread needs about 731.9 N·m (539.8 ft·lb) when dry and 545.5 N·m (402.3 ft·lb) when oiled, tightened to 70% of yield (clamp force 157.9 kN).
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 59.2 kN13313 lbf | 274.5 N·m202.4 ft·lb | 204.6 N·m150.9 ft·lb | 134.7 N·m99.3 ft·lb |
| 4.8 | 79.0 kN17751 lbf | 365.9 N·m269.9 ft·lb | 272.7 N·m201.2 ft·lb | 179.6 N·m132.4 ft·lb |
| 5.6 | 74.0 kN16642 lbf | 343.1 N·m253.0 ft·lb | 255.7 N·m188.6 ft·lb | 168.3 N·m124.2 ft·lb |
| 5.8 | 98.7 kN22189 lbf | 457.4 N·m337.4 ft·lb | 340.9 N·m251.5 ft·lb | 224.4 N·m165.5 ft·lb |
| 6.8 | 118.4 kN26627 lbf | 548.9 N·m404.9 ft·lb | 409.1 N·m301.7 ft·lb | 269.3 N·m198.6 ft·lb |
| 8.8 | 157.9 kN35502 lbf | 731.9 N·m539.8 ft·lb | 545.5 N·m402.3 ft·lb | 359.1 N·m264.9 ft·lb |
| 10.9 | 222.1 kN49925 lbf | 1029.2 N·m759.1 ft·lb | 767.1 N·m565.8 ft·lb | 505.0 N·m372.5 ft·lb |
| 12.9 | 266.5 kN59910 lbf | 1235.0 N·m910.9 ft·lb | 920.5 N·m678.9 ft·lb | 606.0 N·m447.0 ft·lb |
| A2-70 | 111.0 kN24962 lbf | 514.6 N·m379.5 ft·lb | 383.5 N·m282.9 ft·lb | 252.5 N·m186.2 ft·lb |
| A4-70 | 111.0 kN24962 lbf | 514.6 N·m379.5 ft·lb | 383.5 N·m282.9 ft·lb | 252.5 N·m186.2 ft·lb |
| A4-80 | 148.1 kN33283 lbf | 686.1 N·m506.1 ft·lb | 511.4 N·m377.2 ft·lb | 336.7 N·m248.3 ft·lb |
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 64.6 kN14519 lbf | 292.5 N·m215.8 ft·lb | 215.3 N·m158.8 ft·lb | 138.1 N·m101.8 ft·lb |
| 4.8 | 86.1 kN19358 lbf | 390.1 N·m287.7 ft·lb | 287.1 N·m211.7 ft·lb | 184.1 N·m135.8 ft·lb |
| 5.6 | 80.7 kN18148 lbf | 365.7 N·m269.7 ft·lb | 269.1 N·m198.5 ft·lb | 172.6 N·m127.3 ft·lb |
| 5.8 | 107.6 kN24198 lbf | 487.6 N·m359.6 ft·lb | 358.8 N·m264.7 ft·lb | 230.1 N·m169.7 ft·lb |
| 6.8 | 129.2 kN29037 lbf | 585.1 N·m431.5 ft·lb | 430.6 N·m317.6 ft·lb | 276.1 N·m203.7 ft·lb |
| 8.8 | 172.2 kN38716 lbf | 780.1 N·m575.4 ft·lb | 574.1 N·m423.5 ft·lb | 368.2 N·m271.6 ft·lb |
| 10.9 | 242.2 kN54445 lbf | 1097.0 N·m809.1 ft·lb | 807.4 N·m595.5 ft·lb | 517.7 N·m381.9 ft·lb |
| 12.9 | 290.6 kN65334 lbf | 1316.4 N·m970.9 ft·lb | 968.9 N·m714.6 ft·lb | 621.3 N·m458.2 ft·lb |
| A2-70 | 121.1 kN27222 lbf | 548.5 N·m404.6 ft·lb | 403.7 N·m297.7 ft·lb | 258.9 N·m190.9 ft·lb |
| A4-70 | 121.1 kN27222 lbf | 548.5 N·m404.6 ft·lb | 403.7 N·m297.7 ft·lb | 258.9 N·m190.9 ft·lb |
| A4-80 | 161.5 kN36296 lbf | 731.3 N·m539.4 ft·lb | 538.3 N·m397.0 ft·lb | 345.2 N·m254.6 ft·lb |
Torque for M24 hex head bolts and nuts, standard ISO/ASME heads on steel with a 26.0 mm clearance hole. Friction μ applies to both the threads and the bearing face. Always follow the manufacturer's value where one exists.
M24 thread and dimensions
- Coarse thread
- M24×3 — pitch 3 mm
- Fine thread
- M24×2 — pitch 2 mm
- Tensile stress area Aₛ
- 352.5 mm² (coarse), 384.4 mm² (fine)
- Pitch diameter d₂
- 22.052 mm
- Tap drill
- 21 mm (coarse), 22 mm (fine)
- Wrench size (hex head)
- 36 mm
- Clearance hole
- 26.0 mm
How the M24 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 × 352.5 mm² = 157.9 kN
T = F × (0.16·P + 0.58·μ·d₂ + μ·Dₖₘ/2)
T = 157.9 kN × (0.16·3 + 0.58·0.15·22.05 + 0.15·31.00/2) mm = 731.9 N·m
Here d₂ is the pitch diameter and Dₖₘ the effective bearing diameter of the head (31.00 mm). Change the grade, lubrication or preload in the calculator below.
Frequently asked questions
What is the torque for an M24 8.8 bolt?
About 731.9 N·m (539.8 ft·lb) with dry threads, 545.5 N·m (402.3 ft·lb) with oiled threads and 359.1 N·m (264.9 ft·lb) with PTFE or moly paste, for a coarse M24×3 thread tightened to 70% of yield. The resulting clamp force is 157.9 kN.
What is the torque for an M24 10.9 bolt?
About 1029.2 N·m (759.1 ft·lb) with dry threads, 767.1 N·m (565.8 ft·lb) with oiled threads and 505.0 N·m (372.5 ft·lb) with PTFE or moly paste, for a coarse M24×3 thread tightened to 70% of yield. The resulting clamp force is 222.1 kN.
What size wrench fits an M24 bolt?
A standard M24 hex head bolt or nut takes a 36 mm wrench or socket.
What drill size do I need to tap M24?
Use a 21 mm drill for M24×3 and 22 mm for M24×2.