M45 Bolt Torque
An M45 8.8 bolt with a coarse M45×4.5 thread needs about 5052.8 N·m (3726.8 ft·lb) when dry and 3737.0 N·m (2756.3 ft·lb) when oiled, tightened to 70% of yield (clamp force 585.1 kN).
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 219.4 kN49325 lbf | 1894.8 N·m1397.5 ft·lb | 1401.4 N·m1033.6 ft·lb | 908.0 N·m669.7 ft·lb |
| 4.8 | 292.5 kN65767 lbf | 2526.4 N·m1863.4 ft·lb | 1868.5 N·m1378.1 ft·lb | 1210.6 N·m892.9 ft·lb |
| 5.6 | 274.3 kN61656 lbf | 2368.5 N·m1746.9 ft·lb | 1751.7 N·m1292.0 ft·lb | 1135.0 N·m837.1 ft·lb |
| 5.8 | 365.7 kN82208 lbf | 3158.0 N·m2329.2 ft·lb | 2335.6 N·m1722.7 ft·lb | 1513.3 N·m1116.1 ft·lb |
| 6.8 | 438.8 kN98650 lbf | 3789.6 N·m2795.1 ft·lb | 2802.8 N·m2067.2 ft·lb | 1815.9 N·m1339.4 ft·lb |
| 8.8 | 585.1 kN131533 lbf | 5052.8 N·m3726.8 ft·lb | 3737.0 N·m2756.3 ft·lb | 2421.3 N·m1785.8 ft·lb |
| 10.9 | 822.8 kN184969 lbf | 7105.5 N·m5240.8 ft·lb | 5255.2 N·m3876.0 ft·lb | 3404.9 N·m2511.3 ft·lb |
| 12.9 | 987.3 kN221962 lbf | 8526.6 N·m6288.9 ft·lb | 6306.2 N·m4651.2 ft·lb | 4085.9 N·m3013.6 ft·lb |
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 234.8 kN52788 lbf | 1991.0 N·m1468.5 ft·lb | 1457.4 N·m1074.9 ft·lb | 923.8 N·m681.3 ft·lb |
| 4.8 | 313.1 kN70384 lbf | 2654.6 N·m1958.0 ft·lb | 1943.2 N·m1433.2 ft·lb | 1231.7 N·m908.5 ft·lb |
| 5.6 | 293.5 kN65985 lbf | 2488.7 N·m1835.6 ft·lb | 1821.7 N·m1343.6 ft·lb | 1154.7 N·m851.7 ft·lb |
| 5.8 | 391.4 kN87980 lbf | 3318.3 N·m2447.4 ft·lb | 2429.0 N·m1791.5 ft·lb | 1539.6 N·m1135.6 ft·lb |
| 6.8 | 469.6 kN105576 lbf | 3982.0 N·m2936.9 ft·lb | 2914.8 N·m2149.8 ft·lb | 1847.6 N·m1362.7 ft·lb |
| 8.8 | 626.2 kN140769 lbf | 5309.3 N·m3915.9 ft·lb | 3886.3 N·m2866.4 ft·lb | 2463.4 N·m1816.9 ft·lb |
| 10.9 | 880.6 kN197956 lbf | 7466.2 N·m5506.8 ft·lb | 5465.2 N·m4030.9 ft·lb | 3464.2 N·m2555.0 ft·lb |
| 12.9 | 1056.7 kN237547 lbf | 8959.4 N·m6608.1 ft·lb | 6558.2 N·m4837.1 ft·lb | 4157.0 N·m3066.1 ft·lb |
Torque for M45 hex head bolts and nuts, standard ISO/ASME heads on steel with a 48.0 mm clearance hole. Friction μ applies to both the threads and the bearing face. Always follow the manufacturer's value where one exists.
M45 thread and dimensions
- Coarse thread
- M45×4.5 — pitch 4.5 mm
- Fine thread
- M45×3 — pitch 3 mm
- Tensile stress area Aₛ
- 1306.0 mm² (coarse), 1397.7 mm² (fine)
- Pitch diameter d₂
- 42.077 mm
- Tap drill
- 40.5 mm (coarse), 42 mm (fine)
- Wrench size (hex head)
- 70 mm
- Clearance hole
- 48.0 mm
How the M45 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 × 1306.0 mm² = 585.1 kN
T = F × (0.16·P + 0.58·μ·d₂ + μ·Dₖₘ/2)
T = 585.1 kN × (0.16·4.5 + 0.58·0.15·42.08 + 0.15·59.00/2) mm = 5052.8 N·m
Here d₂ is the pitch diameter and Dₖₘ the effective bearing diameter of the head (59.00 mm). Change the grade, lubrication or preload in the calculator below.
Frequently asked questions
What is the torque for an M45 8.8 bolt?
About 5052.8 N·m (3726.8 ft·lb) with dry threads, 3737.0 N·m (2756.3 ft·lb) with oiled threads and 2421.3 N·m (1785.8 ft·lb) with PTFE or moly paste, for a coarse M45×4.5 thread tightened to 70% of yield. The resulting clamp force is 585.1 kN.
What is the torque for an M45 10.9 bolt?
About 7105.5 N·m (5240.8 ft·lb) with dry threads, 5255.2 N·m (3876.0 ft·lb) with oiled threads and 3404.9 N·m (2511.3 ft·lb) with PTFE or moly paste, for a coarse M45×4.5 thread tightened to 70% of yield. The resulting clamp force is 822.8 kN.
What size wrench fits an M45 bolt?
A standard M45 hex head bolt or nut takes a 70 mm wrench or socket.
What drill size do I need to tap M45?
Use a 40.5 mm drill for M45×4.5 and 42 mm for M45×3.