Field note / structural geometry
Most of the useful area is in the flanges.
For bending about the horizontal centroidal axis, the flanges sit far from the centreline. That distance is raised to the third power in the second-moment expression, so overall depth strongly increases Ix and Zx.
The weak axis is a different calculation.
About the vertical centroidal axis, flange width controls the outer-fibre distance and flange contribution. The web is narrow, so Iy and Zy are usually much smaller than the strong-axis values for a conventional beam shape.
What the calculator reports
- Area A is the gross area of two equal flanges plus the clear web.
- Ix and Zx describe the strong-axis geometry through the section depth.
- Iy and Zy describe the weak-axis geometry through the flange width.
- rx and ry are the corresponding radii of gyration, calculated as √(I/A).
What still needs a design check
This is an idealised gross-property tool. It does not check local plate slenderness, lateral-torsional buckling, shear, connections, welds, holes, effective properties, load combinations, material resistance, or serviceability.