Bolt Preload Calculator
Calculate bolt preload, torque requirements, and joint clamping force using the torque-tension relationship T = KFd
Bolt Preload Calculator
Calculate bolt preload torque, stress, and joint separation margin using T = K·F·d.
Formula
M20 = 20 mm | M12 = 12 mm
M20: 245 mm² | M12: 84.3 mm²
Gr 8.8: 600 MPa | 10.9: 830 MPa
Results
Tightening Torque T
200.00 N·m
Bolt Tensile Stress σ_b
204.08 MPa
σ_b / S_p (utilization)
34.0%
FOS Joint Separation
2.500
Recommended F_i (0.75·S_p·A_t)
110250 N
Calculation
T = 0.2 × 50000 N × 20.0 mm = 200.00 N·m
Tensile Stress Areas (ISO metric)
How to Use This Calculator
Enter your input values
Fill in all required input fields for the Bolt Preload Calculator. Most fields include unit selectors so you can work in your preferred unit system.
Review your inputs
Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors.
Read the results
The Bolt Preload Calculator instantly computes the output and displays results with units. All calculations happen in your browser — no loading time and no data sent to a server.
Formula Reference
Bolt Preload Calculator Formula
See calculator inputs for the governing equation
Variables: All variables and their units are labeled in the calculator interface above.
When to Use This Calculator
- •Use the Bolt Preload Calculator when solving homework or exam problems that require quick numerical verification of your hand calculations.
- •Use it during the design phase to rapidly iterate on parameters before running detailed finite element simulations.
- •Use it when reviewing a colleague's calculation or checking a vendor's data sheet for plausibility.
- •Use it to generate reference data for a technical report or presentation without manual computation.
Related Calculators
Shaft Design Calculator
Design solid and hollow shafts under combined bending and torsion using ASME distortion energy criteria
Bearing Life Calculator
Calculate L10 bearing life in revolutions and hours for ball and roller bearings using basic dynamic load rating
Belt Drive Calculator
Calculate belt length, speed ratio, belt tensions, and required belt width for V-belt and flat-belt drives
Helical Spring Design Calculator
Calculate spring rate, deflection, and shear stress with Wahl correction factor for helical compression springs
Weld Strength Calculator
Calculate allowable load and factor of safety for fillet and butt welds under shear, tension, and bending loads
Key and Keyway Calculator
Calculate shear and compressive stress in shaft keys and look up standard ANSI key sizes by shaft diameter