RSJ Beam Calculators Hub
Free planning tools for size, load, weight, deflection, span lookup, padstones, bearing length and cost. Confirm everything with a chartered structural engineer and Building Control before you cut a wall.
Beam Size Calculator
Find the right RSJ beam size for your span and load width. Ideal for wall knock-throughs, extensions and loft openings.
Open Calculator →Load Capacity Calculator
Check bending strength and utilisation for a chosen section and span up to 8 metres.
Open Calculator →Weight Calculator
Convert section and length into total kg, tonnes and self-weight in kN for delivery and crane planning.
Open Calculator →Deflection Calculator
Estimate mid-span sag under uniform load and compare with L/360 or L/250 serviceability limits.
Open Calculator →Cost Calculator
Estimate the total project cost in the UK or Poland, including steel, delivery, engineer fees and installation.
Open Calculator →Span Table Lookup
Pick a clear span and load band for a domestic planning section from our span table.
Open Calculator →Padstone Calculator
Estimate padstone plan size from end reaction and masonry bearing capacity.
Open Calculator →Bearing Length Calculator
Convert clear span into order length by adding bearing at each end.
Open Calculator →Essential Site Equipment
Professional tools recommended for structural work
Professional Engineering Required
These calculators provide estimates only. All structural calculations must be verified by a chartered structural engineer (CEng, MIStructE). Actual structural design must account for deflection limits, lateral stability, local effects, fire protection, and building code requirements.
Never proceed with structural work without:
- Full structural engineer calculations and drawings
- Building Control approval
- Professional indemnity insurance coverage
- Qualified installation by experienced contractors