Type the span and load, get the six lightest sections that stay within both guides.
Free Fabora tool
Free Steel Beam Calculator (UK)
Check a steel beam span in seconds. Pick any of 556 published UK sections, RSJ, UB, UC, PFC, SHS, RHS or CHS, enter the span and load, and compare bending, shear and deflection against clear planning guides. The same engine as the Fabora Steel Tools app.
Beam casesSimply supported, cantilever, and fixed
Sections556 UK sizes: UB, UC, PFC, SHS, RHS, CHS
ChecksBending, shear, deflection, reactions
Use noteIndicative planning tool only
What you get
Beam span, load and deflection checks
For fabricators, site welders, steel erectors, mezzanine fitters and the office. Anyone who wants a quick universal beam, RSJ or hollow section span figure without the faff.
- Spread load, point load, or both together
- Self weight added with one toggle
- S275, S355 and S460 grades plus custom fy
- Utilisation bars for bending, shear and deflection
- Every assumption listed next to the result
- Client-side only with no saved job data
Use note
Planning only, not beam approval
Indicative planning calculator only. This tool gives a quick estimate for beam self weight, bending moment, shear, and deflection from the inputs shown. It does not check lateral-torsional buckling, web bearing, connections or full design-code compliance, and it does not certify a beam or replace structural design. Final beam selection, checks and approval must be completed by a qualified structural engineer or competent designer.
Compare a beam case, section size, load, and span
A steel beam calculator, also called an RSJ calculator, gives a quick planning estimate for a structural steel beam. Enter the section, span and load, and it returns the maximum bending moment, shear force, estimated deflection and support reactions across every published UK RSJ, UB, UC, PFC, SHS, RHS and CHS size. It does not replace structural design or sign-off.
Pick the beam case, choose the section, then enter the span and loads in whatever units suit you. Each check comes back as a utilisation bar against its guide, with every assumption laid out next to the result.
Inputs
Set the beam up in three steps
Pick the beam case, choose a section from the published UK tables, then enter the span and loads.
Results
Enter span and load to calculate
Choose the beam case and section, then add the span and loads to see bending, shear and deflection against the selected guides.
Sizing things up before the real calcs
Use it for the early back-and-forth on a job: what section, how heavy, how much it'll deflect, roughly what stress, while you're still working out which way the design is going.
Good fit for
Planning
Quick checks on span, section size and rough loading.
Trade use
Workshop, office or out on site, wherever the steel talk happens.
The same engine as the Fabora app
This free tool runs the same elastic beam engine as the Fabora Steel Tools app, so the web check and the app check always agree. Bending, shear and deflection, all against clear guides.
556 published UK sections
Every UB, UC, PFC, SHS, RHS and CHS size from the published UK section tables, with real Blue Book properties. Not a cut-down sample list.
Three beam cases, loads combined
Simply supported, cantilever or fixed-ended. Run a spread load in kN/m, drop a point load on top, and let self weight add itself as a full-span UDL.
It won't sign anything off
This is a planning number, nothing more. It doesn't certify the beam, it isn't a design, and it's no replacement for a structural engineer putting their name to the calcs.
Built for the steelwork chat, not the stamped drawing
We've kept it tight on purpose. It gives you a sensible beam estimate for every published UK section and the common load cases. It doesn't pretend to be a design package, and it won't sign anything off.
Fabrication workshops
Sizing up a beam before you cut steel, price a job, or get the designer on the phone. Punch in the span and load and you've got a number to work from.
Site welders and steel erectors
Standing under a span working out if a section looks about right, or whether a load case is one to flag before anyone lifts it into place.
Estimators and office staff
When you just want a quick beam or RSJ load figure for a quote and don't fancy firing up a full structural package to get it.
Keep going
Size charts and section weights
Want the full dimension and weight tables first? The UK steel beam sizes guide lists every UB, UC and RSJ size. And if all you need is the weight of a section, the Steel Weight Calculator does SHS, RHS, UB, UC, PFC, plate and the rest.
Tool FAQ
Short answers on load basis, section data, and use limits
The questions people tend to ask before they trust a steel beam calculator or RSJ span calculator on a real job, including how the shear and deflection guides are worked out.
Keep moving
After more steelwork tools, or help with the paperwork side of a job? There's the full Fabora RAMS product, plus the rest of the Tools section.
What does this steel beam calculator cover?
Mild steel UB, UC, PFC, SHS, RHS and CHS sections, 556 published UK sizes in all, on simply supported, cantilever or fixed-ended beams. Load it with a spread load in kN/m, a point load, or both together, with beam self weight added on top if you keep the toggle on. Out the other end you get the maximum bending moment, shear force, estimated deflection and support reactions, each compared against a clear guide.
What is an RSJ?
RSJ is short for Rolled Steel Joist, the old-school name a lot of people still use for a structural steel beam. These days most beams are universal beams (UB) or universal columns (UC), both of which this tool handles, so when someone asks for an RSJ calculator they're really after a steel beam calculator. Same thing.
Is this a steel beam span calculator?
Yes, that's exactly how most people use it. Enter your span, the section you have in mind and the load, and it shows whether that section sits within the bending, shear and deflection guides at that span. Try a longer or shorter span, or the next section size, and compare. For the tool to pick the lightest passing section for you automatically, that lives in the Fabora Steel Tools app.
Is this an RSJ load calculator?
For the rough early-planning sums people usually mean by that, yes, it'll help. But it's an indicative figure only. The actual beam choice, the proper checks and the sign-off all sit with a structural engineer or a competent designer.
Can it help choose a steel beam size?
It'll give you bending, shear and deflection utilisation so you can hold two or three sections up against each other early on. What it won't do is size the beam for you or stand in for proper calcs signed off by an engineer. The app version adds a suggest mode that lists the lightest sections passing both guides.
How is the spread load (UDL) entered?
In kN per metre of span (or kg per metre if you switch the unit), excluding the beam's own weight. If you're working from a total load, divide it by the span first: 20 kN across a 4 m beam is 5 kN/m. The input helper spells this out so nobody gets caught out.
Does the estimate include beam self weight?
It does, unless you switch it off. The section's own weight is added as a full-length UDL on top of your entered loads, and the results show exactly how many kN/m it contributed.
Does it check shear as well as bending?
Yes. It estimates the average shear stress on the web (or the walls of a hollow section) at peak shear and compares it against fy/√3, the usual yield-based shear guide. Short, heavily loaded spans are often governed by shear, so it's worth seeing. It's still an average-stress planning guide, not a code shear check.
Where do the section properties come from?
All six families use published UK section tables (the Blue Book data): mass per metre, second moment of area and elastic section modulus for every size. Nothing is approximated from the outside dimensions.
What about lateral-torsional buckling?
It isn't calculated, and that matters: an unrestrained UB, UC or PFC can fail by buckling well before the simple bending guide says it's working hard. The tool flags spans that look slender about the minor axis so you know when LTB is likely to govern, but the real LTB check belongs with an engineer.
Does this replace structural design or approval?
Indicative planning calculator only. This tool gives a quick estimate for beam self weight, bending moment, shear, and deflection from the inputs shown. It does not check lateral-torsional buckling, web bearing, connections or full design-code compliance, and it does not certify a beam or replace structural design. Final beam selection, checks and approval must be completed by a qualified structural engineer or competent designer.