A fan wheel (1) is designed as a radial or diagonal fan, comprising a top plate (2) with an inlet port (4), a base plate (6) and a plurality of fan blades (8) distributed around the inlet port (4) and around an axis of rotation (Z). Blade ducts extend (10) respectively between the adjacent fan blades (8). The blade ducts lead radially or diagonally outward from the area of the inlet port (4) and form blow-out ports in the outer region. The blade ducts (10) are designed, with respect to their effective flow cross-section, as large enough that during operation, a turbulent flow with a Reynolds number markedly greater than 2300 is achieved. The top plate (2) or the base plate (6) or both feature a rotationally asymmetrical geometry with a continuous profile, at least in angular sections encompassing the fan blades (8).