5/8" Bolt Torque
A 5/8" Grade 5 bolt with a coarse 5/8"-11 UNC thread needs about 148.4 ft·lb (201.2 N·m) when dry and 111.2 ft·lb (150.8 N·m) when oiled, tightened to 70% of yield (clamp force 64.7 kN).
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| Grade 2 | 40.1 kN9017 lbf | 92.0 ft·lb124.7 N·m | 69.0 ft·lb93.5 N·m | 45.9 ft·lb62.3 N·m |
| Grade 5 | 64.7 kN14547 lbf | 148.4 ft·lb201.2 N·m | 111.2 ft·lb150.8 N·m | 74.1 ft·lb100.5 N·m |
| Grade 8 | 91.5 kN20559 lbf | 209.7 ft·lb284.3 N·m | 157.2 ft·lb213.2 N·m | 104.7 ft·lb142.0 N·m |
| A307 | 25.5 kN5736 lbf | 58.5 ft·lb79.3 N·m | 43.9 ft·lb59.5 N·m | 29.2 ft·lb39.6 N·m |
| A325 | 64.7 kN14547 lbf | 148.4 ft·lb201.2 N·m | 111.2 ft·lb150.8 N·m | 74.1 ft·lb100.5 N·m |
| A490 | 91.5 kN20559 lbf | 209.7 ft·lb284.3 N·m | 157.2 ft·lb213.2 N·m | 104.7 ft·lb142.0 N·m |
| A574 | 105.5 kN23725 lbf | 242.0 ft·lb328.1 N·m | 181.4 ft·lb246.0 N·m | 120.8 ft·lb163.8 N·m |
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| Grade 2 | 45.4 kN10213 lbf | 101.0 ft·lb137.0 N·m | 74.5 ft·lb101.0 N·m | 47.9 ft·lb65.0 N·m |
| Grade 5 | 73.3 kN16475 lbf | 163.0 ft·lb221.0 N·m | 120.1 ft·lb162.9 N·m | 77.3 ft·lb104.8 N·m |
| Grade 8 | 103.6 kN23284 lbf | 230.3 ft·lb312.3 N·m | 169.8 ft·lb230.2 N·m | 109.3 ft·lb148.1 N·m |
| A307 | 28.9 kN6497 lbf | 64.3 ft·lb87.1 N·m | 47.4 ft·lb64.2 N·m | 30.5 ft·lb41.3 N·m |
| A325 | 73.3 kN16475 lbf | 163.0 ft·lb221.0 N·m | 120.1 ft·lb162.9 N·m | 77.3 ft·lb104.8 N·m |
| A490 | 103.6 kN23284 lbf | 230.3 ft·lb312.3 N·m | 169.8 ft·lb230.2 N·m | 109.3 ft·lb148.1 N·m |
| A574 | 119.5 kN26870 lbf | 265.8 ft·lb360.4 N·m | 195.9 ft·lb265.7 N·m | 126.1 ft·lb171.0 N·m |
Torque for 5/8" 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.
5/8" thread and dimensions
- Coarse thread
- 5/8"-11 UNC — pitch 11 TPI
- Fine thread
- 5/8"-18 UNF — pitch 18 TPI
- Tensile stress area Aₛ
- 145.8 mm² (coarse), 165.1 mm² (fine)
- Pitch diameter d₂
- 14.375 mm
- Tap drill
- 17/32 (coarse), 37/64 (fine)
- Wrench size (hex head)
- 15/16"
- Clearance hole
- 17.5 mm
How the 5/8" 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% × 634 MPa × 145.8 mm² = 64.7 kN
T = F × (0.16·P + 0.58·μ·d₂ + μ·Dₖₘ/2)
T = 64.7 kN × (0.16·2.31 + 0.58·0.15·14.38 + 0.15·20.64/2) mm = 201.2 N·m
Here d₂ is the pitch diameter and Dₖₘ the effective bearing diameter of the head (20.64 mm). Change the grade, lubrication or preload in the calculator below.
Frequently asked questions
What is the torque for a 5/8" Grade 5 bolt?
About 148.4 ft·lb (201.2 N·m) with dry threads, 111.2 ft·lb (150.8 N·m) with oiled threads and 74.1 ft·lb (100.5 N·m) with PTFE or moly paste, for a coarse 5/8"-11 UNC thread tightened to 70% of yield. The resulting clamp force is 64.7 kN.
What is the torque for a 5/8" Grade 8 bolt?
About 209.7 ft·lb (284.3 N·m) with dry threads, 157.2 ft·lb (213.2 N·m) with oiled threads and 104.7 ft·lb (142.0 N·m) with PTFE or moly paste, for a coarse 5/8"-11 UNC thread tightened to 70% of yield. The resulting clamp force is 91.5 kN.
What size wrench fits a 5/8" bolt?
A standard 5/8" hex head bolt or nut takes a 15/16" wrench or socket.
What drill size do I need to tap 5/8"?
Use a 17/32 drill for 5/8"-11 UNC and 37/64 for 5/8"-18 UNF.