Squeeze a conductor down to a width comparable to the electron's de Broglie wavelength and its transverse motion snaps into discrete 1D subbands — the same quantum-confinement effect behind quantum wells, wires and dots. This 2D simulator computes the real Landauer-formula conductance from the subband spectrum of a hard-wall square cross-section and renders it two ways at once: a live energy-ladder diagram showing every subband crossing the Fermi level, and a top-down schematic of the channel grid with flowing electrons you can pan and zoom. Sweep the Fermi energy (gate voltage) and watch conduction channels open one at a time, each contributing exactly one quantum G₀ = 2e²/h, while wire width and temperature control how sharp the resulting conductance staircase is.