Bolt Shear Stress Calculator

Inputs

Formula Used

Bolt shear stress is computed from the total applied shear load divided by the effective resisting area.

If shank area is selected, the calculator uses A = πd²/4. Use custom area when the shear plane passes through threads or reduced sections.

How to Use This Calculator

1. Enter the total shear load applied to the joint.
2. Select your load unit and the number of bolts sharing the load.
3. Choose single, double, or triple shear based on joint geometry.
4. Select shank area and provide diameter, or enter a custom shear area.
5. Optionally add an allowable shear stress to get utilization and safety factor.
6. Press Calculate to view results above the form instantly.
7. Use the download buttons to save CSV or PDF outputs.

Example Data Table

These examples show typical inputs and resulting stresses. Values are illustrative.

Bolt Shear Stress Guide

1) What shear stress means

Shear stress is the tangential stress a bolt resists when plates try to slide. This calculator reports stress in MPa and psi. Remember: 1 MPa = 1 N/mm², so using millimeters keeps the math direct and clean for design checks.

2) Core equation and variables

The tool uses τ = V / (n × p × A). Here, V is total shear load, n is bolt count, p is shear planes per bolt, and A is shear area per plane. Increasing n or p reduces stress linearly.

3) Single vs double shear data

In single shear, p = 1. In double shear, p = 2, which ideally halves the stress for the same bolt area. For example, with identical bolts and load, moving from 1 to 2 planes cuts τ by about 50% if load distribution is even.

4) Shank area vs thread area

Shank area uses A = πd²/4. A 12 mm shank gives about 113.10 mm². If the shear plane crosses threads, the effective area is smaller, raising stress. Use the custom area option when you know a reduced net area.

5) Typical load sharing considerations

Real joints rarely share load perfectly. Eccentricity, clearance, and plate stiffness can bias load to a few bolts. A practical approach is to check a conservative case by reducing the effective bolt count or applying a distribution factor before entering V.

6) Built-in unit conversions

The calculator converts 1 lbf = 4.448 N, 1 in = 25.4 mm, and 1 in² = 645.16 mm². Stress converts as 1 MPa ≈ 145.038 psi. These constants help compare catalog data with metric-based joint geometry.

7) Allowable stress and safety outputs

If you enter an allowable shear stress, the tool adds utilization and factor of safety. Utilization is τ/τ_allow. Values under 1.00 indicate the stress is below allowable. Factor of safety is the inverse, τ_allow/τ.

8) Interpreting results with example numbers

Suppose V = 12,000 N, n = 2, p = 1, d = 12 mm. Area per plane is about 113.10 mm², effective area is 226.19 mm², and τ ≈ 53.05 MPa. If allowable is 150 MPa, utilization is about 0.35 and safety factor is about 2.83.

FAQs

1) What is the difference between shear load and shear stress?

Shear load is the total force trying to slide parts. Shear stress is that force divided by resisting area. Stress depends on bolt size, bolt count, and the number of shear planes.

2) When should I choose custom shear area?

Use custom area if the shear plane passes through threads, a reduced shank, or a drilled region. Enter the net area you trust from standards, drawings, or supplier data.

3) Does double shear always cut stress in half?

It halves stress only when both planes carry load evenly and the geometry is symmetric. If clearances or stiffness differences exist, one plane may attract more load.

4) Why does the calculator show MPa and psi?

MPa matches N/mm² and is common in metric design, while psi appears often in catalogs and legacy drawings. Showing both helps you compare results without manual conversions.

5) Can I use this for pins and rivets?

Yes, if the resisting element behaves like a round shank in shear and the load path is similar. Ensure the correct shear area and planes, and confirm any code-specific factors separately.

6) What allowable shear stress should I enter?

Use an allowable value from your design code or material specification. Many standards provide allowables based on bolt grade and safety factors. Avoid guessing when the application is critical.

7) The joint has multiple plates; how do I set shear planes?

Count the shear interfaces crossed by each bolt. A simple lap joint is usually 1 plane. A double-lap joint often has 2 planes. Complex stacks can have more, depending on the load path.