Free 2D Frame Calculator
Run 2D frame analysis online — free, in your browser. Draw your structure, add supports and loads, and get reactions, a free-body diagram and shear, moment and axial diagrams in seconds. No installation, no sign-up to start.
Reactions, free-body diagram and N/V/M diagrams are free. Create a free account to unlock deflections — cloud model storage and sharing are part of Pro.
How to run 2D frame analysis online
- Step 1Draw the frame
Pick the Draw tool and click on the canvas. Every click places a node and connects it to the previous one, so a portal frame takes four clicks. Press Esc to finish a run.
- Step 2Add supports & loads
Right-click a node for its support, a point load or a moment; right-click a member for a distributed load.
- Step 3Adjust anything
Drag nodes to move them, click a load arrow to edit it, type exact values in the side panel, and undo with Ctrl+Z.
- Step 4Solve
Run the analysis to get reactions, a free-body diagram and N, V and M diagrams.
Worked example: simply supported beam
A simply supported steel beam (IPE 180) spans 6.0 m with a pin at the left support and a roller at the right. A central point load of P = 1.2 kN acts downward at mid-span. Below are the support reactions, the equilibrium free-body diagram, and the shear-force (V) and bending-moment (M) diagrams produced by the FERS 2D frame calculator.
| Quantity | Symbol | Value |
|---|---|---|
| Support reaction (each) | Rₐ, R_b | 0.6 kN |
| Maximum bending moment | M_max | 1.8 kN·m |
| Maximum shear force | V_max | 0.6 kN |
| Mid-span deflection | δ | 1.95 mm |
Want a frame rather than a beam? The worked portal frame example solves a 4 m × 3 m portal for reactions, bending moments and deflection — and checks the pinned-base case against the closed-form solution.
Only need a single cantilever? The cantilever beam calculator gives the reactions, shear, moment, deflection and slope for any mix of loads, with the hand calculation written out.
Frequently asked questions
Is the 2D frame calculator free?
Yes. You can draw a 2D frame, add supports and loads, and get the reactions, free-body diagram, the axial (N), shear (V) and bending-moment (M) diagrams and the elastic critical load factor for free, with no sign-up. Creating a free account additionally unlocks the deflected shape and second-order (P-Δ) analysis, and lets you save your model.
Do I need to install anything?
No. The calculator runs entirely in your browser using a WebAssembly finite-element solver — the same engine that powers FERS Cloud. Nothing is uploaded to a server to be solved, so it works offline once loaded.
What can the calculator analyse?
Planar (2D) beams, frames and trusses: nodes, members, pinned, roller, fixed and spring (semi-rigid) supports, point loads, moments, distributed loads and self-weight. Any member end can be released so it carries no moment, and a member can be a beam, a truss (axial-only) bar, or tension-only or compression-only — the last two leave the structure when the force reverses, which is how cross-bracing behaves. It runs a first-order linear elastic analysis and reports support reactions, internal-force diagrams and the elastic critical load factor α_cr; second-order (P-Δ) analysis comes with a free account. Free analyses are limited to 100 members.
How are the bending-moment and shear diagrams calculated?
The frame is solved with the direct stiffness (finite-element) method. Each member's internal forces are sampled along its length to produce continuous N, V and M diagrams. Results match standard beam theory — for example a simply supported beam under a central point load P over a span L gives a peak moment of P·L/4.
Can I see deflections?
The deflected shape and nodal displacements are available once you create a free account. The free, no-sign-up view focuses on equilibrium: reactions, the free-body diagram and the N/V/M force diagrams.
Is this suitable for real structural design?
The calculator is great for learning, checking hand calculations and quick concept design. The critical load factor it reports covers in-plane buckling from the finite-element model and screens out-of-plane buckling member by member on the section's weak axis, taking the buckling length as the member length. A free account lets you download the calculation report, which carries both; for full design — 3D frames, load combinations and Eurocode EC3 steel checks — upgrade to the full FERS Cloud application.
How accurate is 2D frame analysis online compared with a hand calculation?
It solves the same equations. The calculator uses the direct stiffness method, so for cases with a closed-form solution the results agree to within rounding — the worked portal frame example on this site matches the classical pinned-base solution to within 0.04 %. The same model always produces the same reactions and diagrams.
Ready for more than 2D?
Create a free account to unlock deflections, or open the full FERS Cloud app for 3D frames, load combinations and Eurocode EC3 steel checks — Pro adds cloud storage and sharing.