Calculator Inputs
The calculator uses a stacked page layout. The input grid becomes three columns, two columns, or one column by screen size.
Example Data Table
| Case | Diameter (mm) | Bolts | Planes | Area Basis | Design Stress (MPa) | Total Capacity (kN) |
|---|---|---|---|---|---|---|
| Joint A | 12 | 2 | 1 | Shank | 120 | 27.14 |
| Joint B | 16 | 4 | 2 | Threaded, 0.78 factor | 140 | 175.65 |
| Joint C | 20 | 6 | 1 | Shank | 90 | 169.65 |
Formula Used
Agross = π × d² ÷ 4
Aeffective = Agross × area factor
Direct mode: τbase = allowable shear stress
Derived mode: τbase = tensile strength × shear factor
τdesign = τbase ÷ safety factor
Vbolt,plane = Aeffective × τdesign
Vtotal = Vbolt,plane × number of bolts × shear planes
When diameter is in millimeters and stress is in MPa, the result is in newtons because 1 MPa equals 1 N/mm².
How to Use This Calculator
- Enter the bolt diameter in millimeters.
- Choose how many bolts share the applied force.
- Select the number of shear planes in the joint.
- Pick full shank area or reduced threaded area.
- Enter a thread reduction factor when threads cross the shear plane.
- Choose direct allowable stress or derived stress mode.
- Provide stress inputs and add a safety factor.
- Optionally enter the applied load to check pass or fail.
- Click calculate to show results, chart, and export options.
Frequently Asked Questions
1) What does this calculator estimate?
It estimates the shear capacity of a bolted connection. It uses bolt diameter, effective area, allowable or derived stress, bolt count, and shear planes to calculate total resisting force.
2) What is the difference between single and double shear?
Single shear has one resisting plane through each bolt. Double shear has two resisting planes. Double shear usually doubles bolt shear capacity when all other conditions stay equal.
3) Why does area basis matter?
A bolt loaded across the smooth shank has more resisting area than a threaded section. If the shear plane crosses threads, using a reduction factor gives a more realistic capacity estimate.
4) When should I use direct allowable stress mode?
Use direct mode when a code, standard, manufacturer sheet, or project requirement already gives you an allowable shear stress. This makes the result align better with your design basis.
5) When should I use derived stress mode?
Use derived mode when you know tensile strength but not allowable shear stress. The calculator multiplies tensile strength by a shear factor, then divides by the selected safety factor.
6) Does a higher safety factor reduce capacity?
Yes. A larger safety factor lowers design shear stress, which reduces calculated capacity. It creates more conservatism and increases the margin against uncertainty, variation, and unexpected loading.
7) Can this replace structural design codes?
No. This tool is useful for screening and quick checks. Final engineering decisions should follow the governing design code, bolt specification, joint geometry, and project safety requirements.
8) What does fail status mean?
Fail means the applied load exceeds calculated shear capacity. Increase bolt diameter, add more bolts, increase shear planes, improve material strength, or revise the joint design.