Bolt Torque Calculator
Calculate Bolt Torque Requirements
About Bolt Torque Calculations
Proper bolt torque ensures adequate clamping force while preventing bolt failure or joint loosening.
Torque Formula:
T = K × F × D
Where:
- T = Torque (N⋅m or lb⋅ft)
- K = Torque coefficient
- F = Clamping force (N or lb)
- D = Nominal diameter (m or in)
Torque Coefficient (K):
- Dry threads: 0.20-0.30
- Lubricated: 0.15-0.20
- Cadmium plated: 0.16-0.18
- Zinc plated: 0.18-0.22
Bolt Grades:
- 4.6: 400 MPa tensile, 240 MPa yield
- 8.8: 800 MPa tensile, 640 MPa yield
- 10.9: 1000 MPa tensile, 900 MPa yield
- 12.9: 1200 MPa tensile, 1080 MPa yield
Safety Factors:
• General: 1.5-2.0
• Structural: 2.0-3.0
• Automotive: 1.3-1.5
• Aerospace: 1.25-1.5
Proper torque application is critical for joint integrity, preventing both under-tightening and over-tightening failures.