What types of loads can the StructureCalcs beam calculator apply?

It supports four load types: point loads, distributed loads (uniform, triangular, or trapezoidal by setting different intensities at each end), area or pressure loads that are converted to a line load using tributary widths, and applied point moments. You can add as many loads as you like and they are superposed automatically. There is also an optional self-weight load computed from the chosen steel section’s mass per meter (or from the cross-sectional area for a custom section).

Can this beam calculator do continuous, indeterminate, and cantilever beams?

Yes. It solves using the direct stiffness method, which handles both statically determinate and statically indeterminate beams: cantilevers (a single fixed support), simply supported spans, and continuous beams with multiple spans and intermediate supports. You build a multi-span beam by adding rows in the Beam Properties table (each row is one span), and adjacent spans can be joined with either a moment connection (rigid, transferring moment) or a shear connection (an internal hinge with no moment transfer). Pinned, roller, and fixed supports are all available.

What diagrams does the StructureCalcs beam calculator produce?

It generates a beam diagram showing spans, supports and loads, a shear force diagram, a bending moment diagram, and a deflection diagram, along with a support reactions table and a results summary of maximum values. All of the diagrams update instantly as you change any input. You can hover along a diagram to read the exact value at any position via a crosshair and tooltip.

Does the beam calculator calculate deflection?

Yes. It computes the vertical deflection along the entire length of the beam and plots it as a deflection diagram, and the results summary reports the maximum deflection and the position where it occurs. The deflection uses the E and I of the assigned steel section or your own custom values, so you can compare the result against a serviceability limit such as L/250 or L/360.

What is the sign convention in the StructureCalcs beam calculator?

Downward loads are entered as negative and upward loads as positive, and applied moments are positive counter-clockwise. The bending moment diagram uses the US convention by default, plotting sagging (positive) moment above the axis, and a Flip button switches to the opposite convention (for example the Australian sign). Negative deflection is downward.

Can the beam calculator handle stepped sections or different sections along the beam?

Yes, at the span level. Each span is a separate row with its own length, E, and second moment of area, so you can assign a different section to each span, for example a deeper member on a longer span. A single span uses one uniform section, so to create a step you split the beam by adding a span boundary at that point.

How to Use the Beam Calculator: A Complete Guide

A step-by-step tutorial for the StructureCalcs Beam Calculator. Learn how to set up beam properties, add supports and loads, interpret results, and export professional PDF reports.

Getting Started

The StructureCalcs Beam Calculator is a free, browser-based tool that analyzes beams using the direct stiffness method. It handles simply supported beams, cantilevers, continuous beams with multiple spans, and any combination of support types and loading conditions. All calculations run locally in your browser using a compiled Rust/WASM engine — no data is sent to any server, and results appear instantly as you change inputs.

To begin, open the Beam Calculator from the navigation bar. You will see several collapsible input sections: Beam Properties, Supports, Loads, and result sections including Support Reactions, Beam Diagram, and Result Diagrams. You can expand or collapse any section by clicking its header, and reorder them using the arrow buttons if you prefer a different layout.

Before entering data, check the unit system displayed in the navigation bar. Click the unit toggle to switch between SI (meters, kilonewtons, megapascals) and Imperial (feet, kips, ksi). All inputs and outputs update automatically when you switch systems.

Step 1: Define Beam Properties

The Beam Properties section is where you define the physical characteristics of your beam. Each row in the table represents one span of the beam.

For a single-span beam: You will have one row. Enter the span length (e.g., 8 m), and then either select a steel section from the built-in library or enter custom properties manually.

To use a standard steel section: Select the steel standard (AS4100, AISC, EN10365, BS4, JIS, or IS808) from the first dropdown. Then select the section type (e.g., UB, W, IPE) and the specific size (e.g., 310UB40.4, W14x30). The calculator automatically fills in Young’s modulus (E), the second moment of area (Ix), cross-sectional area, and mass per unit length. This eliminates manual data entry and ensures accuracy.

To enter custom properties: Leave the steel standard dropdown empty and type your own values for E and I directly. This is useful for timber beams, concrete sections, aluminum members, or any non-standard cross-section.

For a continuous (multi-span) beam: Click the Add Span button to add more rows. Each row defines one span with its own length and section properties. You can use different sections for different spans — for example, a deeper beam for a longer span. The calculator treats the spans as connected end-to-end, forming a continuous beam.

The connection type between adjacent spans can be set to rigid (moment is transferred across the joint, typical for continuous beams) or hinged (no moment transfer, creating an internal hinge). Most continuous beams use rigid connections.

Step 2: Add Supports

The Supports section defines how the beam is connected to the ground or to other structural elements. Each support is defined by its type and its position along the beam.

Three support types are available:

Pinned (P) — Restrains vertical and horizontal movement but allows rotation. Provides a vertical and horizontal reaction. Use at one end of a simply supported beam.
Roller (R) — Restrains vertical movement only. Provides a vertical reaction. Use at the other end of a simply supported beam, or at intermediate supports of a continuous beam.
Fixed (F) — Restrains all movement and rotation. Provides vertical, horizontal, and moment reactions. Use for cantilever beams or fully fixed ends.

Position is measured from the left end of the beam (position 0). For a single 8 m span simply supported beam, you would add a Pin at position 0 and a Roller at position 8.

Support settlement: If a support displaces vertically (due to foundation movement, for example), you can enter a settlement value. Positive settlement is upward; negative is downward. For most analyses, leave settlement as zero.

Tip: Every beam needs at least enough supports to be stable. A simply supported beam needs one pin and one roller. A cantilever needs one fixed support. A continuous beam needs supports at each intermediate location plus the ends. If your beam is unstable (too few supports), the calculator will display an error.

Step 3: Apply Loads

The Loads section is where you define the forces acting on the beam. Click Add Load to add a new load entry. Four load types are available:

Point load: A concentrated force acting at a single position. Enter the magnitude in kN (SI) or kips (Imperial) and the position along the beam. Negative values act downward (gravity direction); positive values act upward. Common examples: a column bearing on a transfer beam, equipment mounted at a specific point, or a concentrated reaction from another beam.

Distributed load (UDL/trapezoidal): A load spread over a length of the beam. Enter the start position, end position, and the load intensity at each end. For a uniform load, the start and end intensities are equal. For a triangular or trapezoidal load, they differ. Units are kN/m (SI) or kips/ft (Imperial). Common examples: self-weight of a concrete slab, floor live load over a tributary width, or a wall sitting on top of the beam.

Area load: A pressure load (kN/m² or psf) converted to a line load by multiplying by tributary widths. Enter the start and end positions, the pressure, and the tributary widths at each end. This is convenient for floor loading where design codes specify pressures rather than line loads.

Applied moment: A pure rotational force at a specific position. Enter the magnitude in kN·m (SI) or kip·ft (Imperial). Positive moments are counter-clockwise. Applied moments arise from eccentric connections or bracket loads.

You can add as many loads as needed — there is no limit. The calculator superposes all loads automatically. You can also enable self-weight to include the beam’s own weight as a distributed load (calculated from the steel section’s mass per meter).

Step 4: Read the Results

Results update instantly as you change any input. The calculator produces several output sections:

Support Reactions Table: Shows the vertical reaction, horizontal reaction, and moment reaction at each support. Use this to verify equilibrium — the sum of vertical reactions should equal the total applied vertical load. If the numbers do not balance, check your inputs.

Beam Diagram: A visual representation of your beam showing the span lengths, support positions and types, and applied loads. This is a useful sanity check to verify that your model looks correct before interpreting the numerical results.

Shear Force Diagram (SFD): Shows how internal shear force varies along the beam. Look for the maximum absolute value — this is the critical shear for design. Hover over the diagram to see exact values at any position.

Bending Moment Diagram (BMD): Shows how internal bending moment varies along the beam. The maximum positive (sagging) and maximum negative (hogging) moments are the critical values for beam design. You can flip the BMD orientation using the flip button to match your preferred convention.

Deflection Diagram: Shows vertical displacement along the beam. The maximum deflection value and its location are displayed. Compare this against your applicable deflection limit (e.g., L/250 for total deflection, L/360 for live load deflection).

Results Summary: A concise summary of maximum shear, moment, and deflection values with their positions along the beam.

Example 1: Simply Supported Beam with Uniform Load

Problem: A 6 m steel beam (310UB40.4, AS4100) supports a uniform load of 15 kN/m over its entire length. It is simply supported with a pin at the left end and a roller at the right.

Setup in StructureCalcs:

Beam Properties: Span = 6 m, Standard = AS4100, Type = UB, Size = 310UB40.4.
Supports: Pin at 0 m, Roller at 6 m.
Loads: Distributed load from 0 to 6 m, intensity −15 kN/m at both ends (uniform).

Expected results:

Each support reaction: 15 × 6 / 2 = 45 kN upward.
Maximum shear: 45 kN at each support, decreasing linearly to zero at mid-span.
Maximum bending moment: wL²/8 = 15 × 6² / 8 = 67.5 kN·m at mid-span.
Maximum deflection: 5wL⁴/(384EI) ≈ 10.1 mm at mid-span.

Verify these values match the calculator output. The SFD should be a straight line from +45 kN to −45 kN, and the BMD should be a parabola peaking at 67.5 kN·m at mid-span.

Figure 1.The example as the calculator draws it, solved: 45.0 kN at each support — the 45 kN predicted above — with the deflected shape dashed, peaking at 14.65 mm.

Figure 2.Its bending moment diagram: the parabola, peaking at 67.5 kN·m at mid-span. wL²/8, confirmed.

Example 2: Cantilever with a Point Load

Problem: A 3 m cantilever beam (W10x22, AISC) is fixed at the left end and carries a 20 kN point load at the free end (right tip).

Setup in StructureCalcs:

Beam Properties: Span = 3 m, Standard = AISC, Type = W, Size = W10x22.
Supports: Fixed at 0 m. No support at the other end.
Loads: Point load of −20 kN at 3 m.

Expected results:

Fixed support reaction: 20 kN upward and moment reaction of 60 kN·m (counter-clockwise).
Shear force: constant 20 kN along the entire length.
Maximum bending moment: 60 kN·m at the fixed end, decreasing linearly to zero at the free end.
Maximum deflection at the free end: PL³/(3EI).

The entire beam is in hogging (negative moment), with the top fiber in tension. This is characteristic of cantilever beams under downward loads.

Figure 3.The cantilever solved: 20.0 kN vertical reaction and 60.0 kN·m of moment at the fixed end, both matching the hand values above.

Saving, Loading, and Exporting

The calculator provides several options for managing your work:

Save model: Click the Save button to download your beam model as a JSON file. This preserves all inputs — beam properties, supports, loads, and settings — so you can reload the exact same model later. Share the file with colleagues or keep it for your records.

Load model: Click the Load button and select a previously saved JSON file. The calculator restores all inputs and re-runs the analysis automatically.

Export PDF report: Click the PDF button to generate a professional calculation report. The report includes your input data (beam properties, supports, loads), a beam diagram, shear force diagram, bending moment diagram, deflection diagram, and a results summary. You can add a project title, job number, and engineer name to the report header. The PDF is generated entirely in your browser and downloaded instantly.

These features make the calculator suitable not only for quick checks and student assignments but also for documenting preliminary design calculations in professional practice.

Tips for Getting the Best Results

Check your unit system first. Switch to SI or Imperial before entering data. Changing systems mid-way converts all values automatically, but entering data in the wrong system is a common mistake.
Verify equilibrium. The sum of support reactions should equal total applied load. If it does not, you have a modeling error.
Use dark mode for presentations. Toggle dark mode in the nav bar for a professional appearance when sharing your screen or taking screenshots.
Reorder sections to match your workflow. Use the up/down arrows on each section header to arrange the calculator layout in your preferred order.
Compare steel sections quickly. Change the section dropdown and the results update instantly. This makes it easy to iterate toward the lightest section that satisfies deflection and strength requirements.
Include self-weight for accurate results. Enable the self-weight option in the Loads section to automatically include the beam’s own weight as a distributed load.

Troubleshooting Common Issues

If the calculator shows an error or unexpected results, check these common issues:

Singular stiffness matrix: This means the beam is unstable. Ensure you have enough supports to prevent the beam from moving freely. A simply supported beam needs at least a pin and a roller.
No results displayed: Check that you have entered at least one span in Beam Properties, at least two supports (or one fixed support for a cantilever), and at least one load.
Unexpected deflection direction: Remember that negative loads act downward, and negative deflection is downward. If your deflection is upward, verify that your load directions are correct.
Very large deflections: Check that E and I are in the correct units and have realistic values. A missing factor of 10⁶ in I will cause deflections to be a million times too large.
Loads outside the beam span: Ensure all load positions fall within the total beam length. A load at position 10 m on a 6 m beam will cause errors.

Next Steps

Now that you know how to use the calculator, deepen your understanding with these resources:

Open the Beam Calculator — Try it now with your own beam problem.
What Is a Beam? — Learn about different beam types and when to use each.
Understanding SFD & BMD — Deep dive into interpreting shear force and bending moment diagrams.
Steel Section Properties — Understand the section properties used by the calculator.
Truss Analysis Guide — Learn how to use the companion truss calculator.

Frequently asked questions

What types of loads can the StructureCalcs beam calculator apply?: It supports four load types: point loads, distributed loads (uniform, triangular, or trapezoidal by setting different intensities at each end), area or pressure loads that are converted to a line load using tributary widths, and applied point moments. You can add as many loads as you like and they are superposed automatically. There is also an optional self-weight load computed from the chosen steel section’s mass per meter (or from the cross-sectional area for a custom section).
Can this beam calculator do continuous, indeterminate, and cantilever beams?: Yes. It solves using the direct stiffness method, which handles both statically determinate and statically indeterminate beams: cantilevers (a single fixed support), simply supported spans, and continuous beams with multiple spans and intermediate supports. You build a multi-span beam by adding rows in the Beam Properties table (each row is one span), and adjacent spans can be joined with either a moment connection (rigid, transferring moment) or a shear connection (an internal hinge with no moment transfer). Pinned, roller, and fixed supports are all available.
What diagrams does the StructureCalcs beam calculator produce?: It generates a beam diagram showing spans, supports and loads, a shear force diagram, a bending moment diagram, and a deflection diagram, along with a support reactions table and a results summary of maximum values. All of the diagrams update instantly as you change any input. You can hover along a diagram to read the exact value at any position via a crosshair and tooltip.
Does the beam calculator calculate deflection?: Yes. It computes the vertical deflection along the entire length of the beam and plots it as a deflection diagram, and the results summary reports the maximum deflection and the position where it occurs. The deflection uses the E and I of the assigned steel section or your own custom values, so you can compare the result against a serviceability limit such as L/250 or L/360.
What is the sign convention in the StructureCalcs beam calculator?: Downward loads are entered as negative and upward loads as positive, and applied moments are positive counter-clockwise. The bending moment diagram uses the US convention by default, plotting sagging (positive) moment above the axis, and a Flip button switches to the opposite convention (for example the Australian sign). Negative deflection is downward.
Can the beam calculator handle stepped sections or different sections along the beam?: Yes, at the span level. Each span is a separate row with its own length, E, and second moment of area, so you can assign a different section to each span, for example a deeper member on a longer span. A single span uses one uniform section, so to create a step you split the beam by adding a span boundary at that point.