Steel Beam Calculator

A Starting Point for Structural Design

This calculator provides a simplified analysis for a uniformly loaded steel beam, helping you estimate the required beam section for a given span and load. This tool is for educational and preliminary estimation purposes only. All structural designs must be verified by a qualified professional engineer.

The Formulas Explained

The calculation is based on two key principles of structural mechanics:

• Maximum Bending Moment (M): For a simply supported, uniformly loaded beam, the maximum moment occurs at the center. M = (w * L²) / 8, where w is the load per unit length and L is the span.
• Required Section Modulus (S): S = M / F_b, where F_b is the allowable bending stress of the steel. The calculator uses these values to suggest a generic beam size (e.g., 'W10x12').

How to Use the Calculator

1. Beam Span (ft): Enter the length of the beam between supports in feet.
2. Load on Beam (kips/ft): Enter the uniform load applied to the beam in kips per linear foot (1 kip = 1000 pounds).
3. Calculate: The tool will suggest a potential steel beam section.

Real-World Example

A steel beam needs to span 20 feet and support a uniform load of 1.5 kips/ft.

• Max Bending Moment (M): (1.5 * 20²) / 8 = 75 kip-ft.
• The calculator would then use this moment to find a required section modulus and suggest an appropriate beam size from a lookup table.

Frequently Asked Questions (FAQ)

• What does a beam designation like 'W8x10' mean? 'W' stands for a wide-flange beam, the most common shape. The '8' is the nominal depth of the beam in inches. The '10' is the weight of the beam in pounds per foot.
• Does this calculator consider deflection? No. This is a major simplification. In real-world design, the amount the beam bends (deflection) is often the controlling factor, not just its strength. A professional design will always check for deflection.
• Can I use this for my home renovation project? You can use it to get a very rough preliminary idea, but you must consult a structural engineer before purchasing materials or beginning construction. They will account for all loads (dead, live, snow, etc.), local building codes, and other critical factors.