M27 Bolt Torque
An M27 8.8 bolt with a coarse M27×3 thread needs about 1074.4 N·m (792.4 ft·lb) when dry and 797.2 N·m (588.0 ft·lb) when oiled, tightened to 70% of yield (clamp force 205.8 kN).
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 77.2 kN17351 lbf | 402.9 N·m297.2 ft·lb | 299.0 N·m220.5 ft·lb | 195.0 N·m143.8 ft·lb |
| 4.8 | 102.9 kN23134 lbf | 537.2 N·m396.2 ft·lb | 398.6 N·m294.0 ft·lb | 260.0 N·m191.8 ft·lb |
| 5.6 | 96.5 kN21688 lbf | 503.6 N·m371.5 ft·lb | 373.7 N·m275.6 ft·lb | 243.8 N·m179.8 ft·lb |
| 5.8 | 128.6 kN28918 lbf | 671.5 N·m495.3 ft·lb | 498.3 N·m367.5 ft·lb | 325.1 N·m239.7 ft·lb |
| 6.8 | 154.4 kN34702 lbf | 805.8 N·m594.3 ft·lb | 597.9 N·m441.0 ft·lb | 390.1 N·m287.7 ft·lb |
| 8.8 | 205.8 kN46269 lbf | 1074.4 N·m792.4 ft·lb | 797.2 N·m588.0 ft·lb | 520.1 N·m383.6 ft·lb |
| 10.9 | 289.4 kN65065 lbf | 1510.9 N·m1114.4 ft·lb | 1121.1 N·m826.9 ft·lb | 731.4 N·m539.4 ft·lb |
| 12.9 | 347.3 kN78079 lbf | 1813.1 N·m1337.3 ft·lb | 1345.4 N·m992.3 ft·lb | 877.6 N·m647.3 ft·lb |
| A2-70 | 144.7 kN32533 lbf | 755.4 N·m557.2 ft·lb | 560.6 N·m413.5 ft·lb | 365.7 N·m269.7 ft·lb |
| A4-70 | 144.7 kN32533 lbf | 755.4 N·m557.2 ft·lb | 560.6 N·m413.5 ft·lb | 365.7 N·m269.7 ft·lb |
| A4-80 | 193.0 kN43377 lbf | 1007.3 N·m742.9 ft·lb | 747.4 N·m551.3 ft·lb | 487.6 N·m359.6 ft·lb |
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 83.3 kN18723 lbf | 426.1 N·m314.2 ft·lb | 312.6 N·m230.6 ft·lb | 199.1 N·m146.9 ft·lb |
| 4.8 | 111.0 kN24964 lbf | 568.1 N·m419.0 ft·lb | 416.8 N·m307.4 ft·lb | 265.5 N·m195.8 ft·lb |
| 5.6 | 104.1 kN23404 lbf | 532.6 N·m392.8 ft·lb | 390.7 N·m288.2 ft·lb | 248.9 N·m183.6 ft·lb |
| 5.8 | 138.8 kN31205 lbf | 710.1 N·m523.7 ft·lb | 521.0 N·m384.3 ft·lb | 331.9 N·m244.8 ft·lb |
| 6.8 | 166.6 kN37446 lbf | 852.1 N·m628.5 ft·lb | 625.2 N·m461.1 ft·lb | 398.2 N·m293.7 ft·lb |
| 8.8 | 222.1 kN49928 lbf | 1136.1 N·m838.0 ft·lb | 833.6 N·m614.8 ft·lb | 531.0 N·m391.6 ft·lb |
| 10.9 | 312.3 kN70211 lbf | 1597.7 N·m1178.4 ft·lb | 1172.2 N·m864.6 ft·lb | 746.7 N·m550.7 ft·lb |
| 12.9 | 374.8 kN84254 lbf | 1917.2 N·m1414.1 ft·lb | 1406.6 N·m1037.5 ft·lb | 896.0 N·m660.9 ft·lb |
| A2-70 | 156.2 kN35106 lbf | 798.8 N·m589.2 ft·lb | 586.1 N·m432.3 ft·lb | 373.4 N·m275.4 ft·lb |
| A4-70 | 156.2 kN35106 lbf | 798.8 N·m589.2 ft·lb | 586.1 N·m432.3 ft·lb | 373.4 N·m275.4 ft·lb |
| A4-80 | 208.2 kN46808 lbf | 1065.1 N·m785.6 ft·lb | 781.5 N·m576.4 ft·lb | 497.8 N·m367.2 ft·lb |
Torque for M27 hex head bolts and nuts, standard ISO/ASME heads on steel with a 30.0 mm clearance hole. Friction μ applies to both the threads and the bearing face. Always follow the manufacturer's value where one exists.
M27 thread and dimensions
- Coarse thread
- M27×3 — pitch 3 mm
- Fine thread
- M27×2 — pitch 2 mm
- Tensile stress area Aₛ
- 459.4 mm² (coarse), 495.7 mm² (fine)
- Pitch diameter d₂
- 25.052 mm
- Tap drill
- 24 mm (coarse), 25 mm (fine)
- Wrench size (hex head)
- 41 mm
- Clearance hole
- 30.0 mm
How the M27 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 × 459.4 mm² = 205.8 kN
T = F × (0.16·P + 0.58·μ·d₂ + μ·Dₖₘ/2)
T = 205.8 kN × (0.16·3 + 0.58·0.15·25.05 + 0.15·35.50/2) mm = 1074.4 N·m
Here d₂ is the pitch diameter and Dₖₘ the effective bearing diameter of the head (35.50 mm). Change the grade, lubrication or preload in the calculator below.
Frequently asked questions
What is the torque for an M27 8.8 bolt?
About 1074.4 N·m (792.4 ft·lb) with dry threads, 797.2 N·m (588.0 ft·lb) with oiled threads and 520.1 N·m (383.6 ft·lb) with PTFE or moly paste, for a coarse M27×3 thread tightened to 70% of yield. The resulting clamp force is 205.8 kN.
What is the torque for an M27 10.9 bolt?
About 1510.9 N·m (1114.4 ft·lb) with dry threads, 1121.1 N·m (826.9 ft·lb) with oiled threads and 731.4 N·m (539.4 ft·lb) with PTFE or moly paste, for a coarse M27×3 thread tightened to 70% of yield. The resulting clamp force is 289.4 kN.
What size wrench fits an M27 bolt?
A standard M27 hex head bolt or nut takes a 41 mm wrench or socket.
What drill size do I need to tap M27?
Use a 24 mm drill for M27×3 and 25 mm for M27×2.