Can I calculate a residential mezzanine with steel beams?

Yes. CalcSteel handles residential mezzanines well — typical scenario: 2 or 3 beams spanning 4-6 m supporting a 20 mm OSB or plywood deck with tiled floor. Model the beams as simply supported or continuous depending on the support conditions, apply dead load (2.0 kN/m² for deck + tiles) and live load (2.0-3.0 kN/m² per NBR 6120 / ASCE 7 for residential), run analysis, check flexure + shear + deflection. The key serviceability criterion is usually deflection: L/360 for live load, L/240 for total load — mezzanines with higher deflection tend to feel bouncy. Common profiles: IPE 200-300, W 200-250, or built-up sections for longer spans. Don't forget to check beam-to-beam and beam-to-wall connections separately.