Donor mass immediately after Case AB mass transfer (M_AB) in units of the solar mass (top and middle) and in units of the donor mass after Case B mass transfer (M_B, bottom), as a function of the initial orbital period P_ini, with the initial donor mass M_ini colour-coded (top and bottom). The middle panel shows M_AB as a function of the initial donor mass, where models with the same initial orbital period are indicated with the same colour. Each cross represents the median of M_AB across different initial mass ratios and in the top plots we indicted in black its interquartile range (distance from first to third quartile of the mass ratio distribution). In the middle plots the black lines show the mass of the convective cores of single stars at the beginning (M_ZAMS^conv.core) and the end (M_TAMS^conv.core) of core hydrogen-burning, as well as the mass after Case B mass transfer, as a function of the initial stellar mass. Grey lines indicate our best fit to the data. The panels on the left show LMC models, and on the right SMC show models.