Magnetic cell separation has become a popular technique to enrich or deplete cells of interest from a heterogeneous cell population. One important aspect of magnetic cell separation is the degree to which a cell binds paramagnetic material. It is this paramagnetic material that imparts a positive magnetophoretic mobility to the target cell, thus allowing effective cell separation. A mathematical relationship has been developed to correlate magnetic labeling to the magnetophoretic mobility of an immunomagnetically labeled cell. Four parameters have been identified that significantly affect magnetophoretic mobility of an immunomagnetically labeled cell: the antibody binding capacity (ABC) of a cell population, the secondary antibody amplification (ψ), the particle-magnetic field interaction parameter (ΔχVm), and the cell diameter (Dc). The ranges of these parameters are calculated and presented along with how the parameters affect the minimum and maximum range of magnetophoretic mobility. A detailed understanding of these parameters allows predictions of cellular magnetophoretic mobilities and provides control of cell mobility through selection of antibodies and magnetic particle conjugates.