Beam Deflection Calculator
Calculate max deflection of simply supported and cantilever beams.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
Can't find what you need?
Request a ToolHow to Use the Beam Deflection Calculator
Select the beam type, enter the load, length, elastic modulus, and moment of inertia to calculate maximum deflection.
- Select beam type. Choose from simply supported or cantilever with point or uniform load.
- Enter parameters. Load in Newtons (or N/m for distributed), length in meters.
- Read the result. Deflection appears in meters and millimeters.
About the Beam Deflection Calculator
Beam deflection is the displacement of a structural member under load. Engineers must ensure deflection stays within acceptable limits to prevent structural failure and maintain serviceability. The deflection depends on the beam configuration, load type, material stiffness (elastic modulus), and cross-section geometry (moment of inertia). Simply supported beams deflect less than cantilevers under the same load because they have two support points distributing the reaction forces.
Frequently Asked Questions
What is an acceptable beam deflection?
Typical building codes limit deflection to L/360 for floors and L/240 for roofs, where L is the span length. Industrial applications may allow more or less depending on function.
What is the moment of inertia?
The moment of inertia (second moment of area) measures a cross-section's resistance to bending. A larger I means less deflection. It depends on the shape and size of the cross-section.
How does beam length affect deflection?
Deflection increases with the cube or fourth power of length (depending on load type), so doubling the span increases deflection by 8x to 16x.