Bolt Torque Calculator
Calculate the tightening torque for bolts based on bolt size, grade, and lubrication conditions. Enter the bolt diameter (size), grade, and lubrication type to get the recommended torque.
0.00 N·m
Recommended Tightening Torque
Clamp Force: 0.00 kN
Bolt Stress: 0.00 MPa
Bolt Stress: 0.00 MPa
Bolt Torque Calculation
This bolt torque calculator is the proper tightening torque for bolts based on their size, material grade, and lubrication conditions. Proper torque is essential for correct clamp force without damaging the bolt.
Torque Calculation Formula:
T = K × F × D
Where:
- T = Torque (N·m or ft·lb)
- K = Nut factor (coefficient of friction)
- F = Clamp force (N or lb)
- D = Nominal bolt diameter (m or ft)
F = (σ × At)
Where:
- σ = Proof stress (MPa)
- At = Tensile stress area (mm²)
Bolt Grades and Proof Stress:
| Grade | Proof Stress (MPa) | Yield Stress (MPa) | Tensile Stress (MPa) |
|---|---|---|---|
| 4.6 | 240 | 240 | 400 |
| 5.8 | 380 | 400 | 520 |
| 8.8 | 600 | 640 | 800 |
| 10.9 | 830 | 900 | 1040 |
| 12.9 | 970 | 1100 | 1220 |
| A2-70 | 450 | 450 | 700 |
| A4-80 | 600 | 600 | 800 |
Bolt Torque Values
| Bolt Size (mm) | Pitch (mm) | Stress Area (mm²) | Torque (N·m) | Torque (ft·lb) |
|---|---|---|---|---|
| M6 | 1.0 | 20.1 | 8 | 5.9 |
| M8 | 1.25 | 36.6 | 20 | 14.8 |
| M10 | 1.5 | 58.0 | 40 | 29.5 |
| M12 | 1.75 | 84.3 | 70 | 51.6 |
| M14 | 2.0 | 115.0 | 115 | 84.8 |
| M16 | 2.0 | 157.0 | 175 | 129.1 |
| M20 | 2.5 | 245.0 | 340 | 250.8 |
| M24 | 3.0 | 353.0 | 590 | 435.2 |
| M30 | 3.5 | 561.0 | 1170 | 862.9 |
| M36 | 4.0 | 817.0 | 2050 | 1512.0 |
