The saturation magnetization of gallium‐substituted yttrium iron garnet single crystals of composition Y3[Fe2−xGax](Fe3−yGay) O12with 0≤x+y≤1.5 has been investigated in the temperature range 4.2≤T≤Tc. The magnetization values are below most data of previous investigations on this system. From the fit of the molecular field theory to the experimental results atT=4.2 K the fraction of the tetrahedral gallium ionsft=y/(x+y) could be deduced and are found to range between 1 and 0.91 for 0≤x+y≤1.5. The compensation temperature occurring forx+y>1 has been studied as a function of the gallium distribution.