Guidance, not a calculator
Beams, lintels and structural sizes
Sizing a beam, lintel, joist or steel, or taking out a wall, is structural design. It needs a structural engineer.
What the work involves
A beam or lintel carries everything above it: floors, roof, walls, and the people and furniture on them. Sizing one means tracing those loads down through the building, choosing the member and its bearings at each end, and checking that the walls and foundations below can take the extra weight.
Why it's regulated
Structural alterations need building regulations approval in the UK, and an engineer's or architect's design in France and Spain. A member that's too small can sag, crack the walls above or fail, and the loads in an older house are rarely what they seem.
Who to ask
A structural engineer designs and sizes the beam or lintel and provides the calculations building control asks for. Your builder then installs it to that design, propping the structure while the wall is open.
No figures here, on purpose. We don't give sizes, rules of thumb or typical values for this work. Only a qualified professional who has seen your building can.