This diagram shows the luminosity classes of stars in relation to their mass and diameter. As one can read correlate all 3 sizes, from a few outliers aside. The more mass a star has, the greater is its diameter.
Also, the diameter increases with age and stage of the star (eg, giant stars - luminosity class III). The exception is the white dwarf stars (luminosity class VII) which are located at the bottom of the y-axis. In this final stage will take no more nuclear fusion, whereby the mass was compressed to a very small diameter.