Formula Used
Self weight: wself = γ × b × d
Total service uniform load: w = dead load + live load + construction load + self weight
Left reaction: RA = wL / 2 + P(L - a) / L
Right reaction: RB = wL / 2 + Pa / L
Moment at any point: M(x) = RAx - wx² / 2 - P(x - a), when x ≥ a
Shear at any point: V(x) = RA - wx - P, when x ≥ a
Curvature relation: d²y / dx² = M / EI
Bending stress: σ = M / S
Approximate rectangular shear stress: τ = 1.5V / A
Allowable deflection: Δallow = L / selected ratio
How to Use This Calculator
Enter the clear beam span first. Add the beam width and depth. Use custom section properties when checking a manufactured shape.
Enter dead, live, construction, and point loads. Place the point load from the left support. Add material stiffness and allowable stress limits.
Press the calculate button. The result appears above the form and below the header. Review reactions, moment, shear, deflection, stress, and utilization.
Use the CSV button for spreadsheet records. Use the PDF button for a printable project note.
Example Data Table
| Case |
Span |
Size |
Dead Load |
Live Load |
Point Load |
Point Position |
Typical Use |
| Light floor beam |
4.0 m |
100 × 250 mm |
1.2 kN/m |
2.0 kN/m |
2.0 kN |
2.0 m |
Small room framing |
| Deck support beam |
5.0 m |
150 × 300 mm |
1.5 kN/m |
3.0 kN/m |
4.0 kN |
2.5 m |
Outdoor platform |
| Construction staging |
6.0 m |
200 × 350 mm |
2.0 kN/m |
3.5 kN/m |
6.0 kN |
3.0 m |
Temporary loading |
Beam Load Span Guide
Why Span Checks Matter
Beam load span checks help builders make early decisions before detailed design starts. A beam must carry loads without unsafe bending, high shear, or visible sag. This calculator gives a practical estimate for a simply supported member. It combines uniform loads, point loads, self weight, section properties, and service limits.
Understanding the Inputs
A span is the clear distance between supports. Longer spans increase bending quickly. Uniform load represents weight spread along the beam. Dead load may include finishes and fixed materials. Live load may include people, stored items, or temporary construction loads. A point load represents a concentrated machine, post, or heavy item. Its position changes each support reaction.
The tool uses service loads for deflection. It uses factored loads for strength checks. This separation is important. A beam may be strong enough, yet still feel bouncy. Another beam may meet sag limits, yet fail bending stress. Review both results before selecting a member.
Section Properties and Limits
The section inputs estimate stiffness and stress. Width and depth form a rectangular section. You may also enter custom moment of inertia and section modulus. That helps when checking steel shapes, engineered timber, or built-up members. Elastic modulus affects deflection. Allowable bending and shear stress affect utilization.
Self weight is optional. It is calculated from section size and material unit weight. This is useful for concrete and heavy timber checks. Small beams may have low self weight. Large members can add significant permanent load.
Using Results Safely
Maximum moment is found from the combined bending diagram. Reactions are based on static equilibrium. Deflection is estimated by integrating curvature along the span. The result is an estimate, not a stamped design.
Construction conditions can be demanding. Wet materials, stacked boards, workers, and equipment may create short term loads. Use realistic values. Do not ignore temporary bracing, lateral support, bearing length, holes, notches, or connection capacity.
Use this calculator for planning, comparison, and teaching. It can help compare depths, spans, and load cases quickly. Final beam selection should follow local codes. It should also be reviewed by a qualified professional when safety, permits, or public use are involved. Record assumptions beside each result. Small input changes can shift demand. Keep copies for coordination, review, estimating, field discussion, and future project reference notes carefully.
FAQs
1. What does this beam load span calculator check?
It estimates support reactions, shear, bending moment, deflection, bending stress, shear stress, and utilization for a simply supported beam with uniform and point loads.
2. Can I use it for steel beams?
Yes. Enter the correct elastic modulus, moment of inertia, section modulus, and allowable stresses for the selected steel member.
3. Why is self weight included?
Self weight is a permanent load. It can become important for large timber, concrete, or heavy built-up members.
4. What is the point load position?
It is the distance from the left support to the concentrated load. Moving it changes reactions, moment, shear, and deflection.
5. Why are service and factored loads different?
Service loads are commonly used for deflection checks. Factored loads are used for strength checks, based on selected load factors.
6. What does utilization mean?
Utilization compares calculated demand with the entered allowable limit. A value under 100 percent means the entered limit is not exceeded.
7. Is this a final structural design tool?
No. It is an estimating and planning tool. Final design must follow local codes and professional engineering requirements.
8. What if I know exact beam properties?
Enter custom moment of inertia and section modulus. These values override the rectangular estimates from width and depth.