How to use this calculator
- Enter the force. Enter the total shear load the pin must carry.
- Enter allowable shear. Use the material allowable shear stress before safety factor unless it is already derated.
- Choose shear planes. Use 1 for single shear or 2 for double shear clevis joints.
- Set safety factor. The calculator divides allowable shear by this factor.
- Round up. Choose the next standard pin size and check bearing, bending and edge distance.
How it works
A round shear pin resists load through the pin area cut by one or more shear planes:
tau = F / (n · A), where A = pi · d^2 / 4
Here F is total force, n is shear-plane count and
A is the pin area on one plane.
The calculator first derates the allowable stress by your safety factor:
tau_d = tau_allow / N. It then solves directly for diameter:
d = sqrt(4F/(pi·n·tau_d)). Double shear doubles the available shear
area, so it reduces the required diameter by a factor of sqrt(2) versus
single shear for the same force and stress.
Worked example
Verified against the live calculator
A double-shear pin carrying 10,000 N with allowable shear
120 MPa and safety factor 2 has design shear
60 MPa. Each of the two shear planes carries
5,000 N, and the required pin area per plane is
10000 / (2 x 60) = 83.33 mm^2.
The diameter is d = sqrt(4 x 83.33 / pi) = 10.30 mm. In practice you
would pick the next standard diameter, then check the plates for bearing and tear-out.
Frequently asked questions
How do I calculate shear pin diameter?
Average pin shear stress is tau = F/(nA), where F is total shear force, n is the number of shear planes and A = pi d^2/4 is the round pin area. Solving for diameter gives d = sqrt(4F/(pi n tau_d)).
What is the difference between single shear and double shear?
Single shear has one plane cutting the pin. Double shear has two planes, as in a clevis or double-lap joint, so the same load is shared by twice the shear area and the required diameter is smaller.
What shear stress should I enter?
Enter the material allowable shear stress before safety factor, or enter an already-derated design stress and set safety factor to 1. Do not use tensile yield directly unless your design method explicitly converts it to allowable shear.
Does this check bearing pressure in the holes?
No. The calculator checks direct average shear through the pin only. The pin can still fail by bending, or the plates can fail by bearing, tear-out, edge distance, net section or fatigue.
Can I use this for bolts?
For a plain pin or dowel, this calculator is appropriate. For threaded bolts, use the bolt shear strength calculator because the shear area depends on whether the thread or shank crosses the shear plane.
Does this work in metric and imperial?
Yes. Enter force in N or lbf, stress in MPa or ksi and the result in mm or inches. Unit conversion happens before the formula runs.
Method & assumptions
- Average direct shear through a round pin: uniform stress on each shear plane.
- Load is shared equally across the entered number of shear planes.
- Pin bending, bearing pressure, plate tear-out, edge distance, clearance, shock, fatigue and retaining features are not checked.
- Threaded fasteners should use a threaded bolt shear calculation because the area may be the tensile stress area, not the shank area.