Use this bolt tensile stress calculator to calculate the axial tensile stress in a bolt from applied tensile load and bolt diameter. The calculator determines bolt area, tensile stress, design allowable stress, utilisation, factor of safety and pass/fail result.
This calculator checks a bolt subjected to axial tensile loading. It uses the bolt diameter to calculate the cross-sectional area and then divides the tensile load by this area to calculate tensile stress.
The calculator provides:
This calculator is useful for simple bolt tensile load checks, preliminary fastener sizing and comparing bolt stress against an allowable or yield stress.
Bolt cross-sectional area:
Tensile stress:
Design allowable tensile stress:
Utilisation:
Factor of safety:
| Symbol | Description | Units |
|---|---|---|
| Ft | Axial tensile load | N |
| d | Bolt diameter or effective diameter | mm |
| A | Bolt cross-sectional area | mm² |
| σ | Tensile stress | N/mm² |
| σallow | Allowable or yield stress | N/mm² |
| SF | Safety factor | - |
| FoS | Factor of safety | - |
Enter the bolt tensile load and diameter, then click calculate.
| Result | Meaning |
|---|---|
| Bolt area | The cross-sectional area calculated from the entered bolt diameter. |
| Tensile stress | The axial tensile load divided by the bolt area. |
| Design allowable stress | The entered allowable or yield stress divided by the safety factor. |
| Utilisation | The calculated tensile stress divided by the design allowable stress. A value below 100% passes this simplified check. |
| Factor of safety | The entered allowable or yield stress divided by the calculated tensile stress. |
This calculator provides a simplified axial tensile stress check for a bolt. It does not check every possible fastener or joint failure mode.
| This Calculator Includes | This Calculator Does Not Include |
|---|---|
| Axial tensile stress from applied load | Thread stripping |
| Circular bolt area from entered diameter | Nut strength or tapped hole strength |
| Utilisation and factor of safety | Joint stiffness and load sharing |
| Worked calculation | Fatigue or fluctuating load checks |
| Force unit conversion | Prying action or plate bending |
For combined tensile and shear stress, use the Bolt Combined Stress Calculator.
For estimating preload from torque, use the Bolt Preload Calculator.
For checking bolt shear stress, use the Bolt Shear Stress Calculator.
Bolt tensile stress is calculated by dividing the axial tensile load by the effective bolt area. For a plain shank, the circular area based on the shank diameter may be suitable. For a threaded section, the tensile stress area or thread root area is often more appropriate.
The entered allowable or yield stress should be selected by the engineer based on bolt grade, material strength, design standard and the required safety margin.
In many real bolted joints, the bolt stress is also affected by preload, joint stiffness, external load sharing, prying action and fatigue. These effects should be considered separately where relevant.
For further bolted joint theory, see the RoyMech reference page: Bolted Joint Design and Calculations.
For the full calculator section, see: Bolted Joint Calculators.
Bolt tensile stress is calculated by dividing the axial tensile load by the bolt cross-sectional area:
Use the area at the critical section. For a plain shank check, the shank area may be used. If the threaded section is critical, the tensile stress area or thread root area may be more appropriate.
No. Tensile stress is the stress in the bolt caused by tensile force. Preload is the initial tensile force introduced by tightening the bolt.
Yes, but the entered diameter should represent the effective diameter at the critical section. For threaded bolts, a tensile stress area calculator may give a better area than using nominal bolt diameter.
No. This calculator checks axial tensile stress only. For combined tensile and shear loading, use the Bolt Combined Stress Calculator.
This calculator is intended for preliminary engineering calculations and educational use. Final fastener design should be checked against the relevant design standard, bolt grade, thread engagement, fatigue requirements and safety factors.