Your question is unclear. Are you asking how does one calculate the size of a star, or what property of a star determines its size? I'm guessing the latter. In that case, the size of a star is directly related to its mass. The mass a star has collected when it formed, the larger the star will be.
The two major factors that determine the size of a star are its mass and its age. A star's mass dictates how much material there is to form the star, while its age influences the stage of its life cycle, which in turn affects its size.
Three physical factors that determine a star's brightness are its temperature (hotter stars are brighter), size (larger stars are generally brighter), and distance from Earth (the closer a star is, the brighter it appears).
distance from the sun and the age of the star
The two main factors that determine the characteristics of a star are its mass and its age. The mass of a star determines its temperature, size, luminosity, and lifespan. A star's age affects its stage in its life cycle, such as whether it is a young, main-sequence star or an older red giant.
To determine a star's luminosity, one can measure its apparent brightness as seen from Earth and correct for distance. Using this information along with the star's surface temperature, one can apply the Stefan-Boltzmann law to calculate the star's luminosity. This process allows astronomers to compare the intrinsic brightness of stars regardless of their distance from Earth.
The two major factors that determine the size of a star are its mass and its age. A star's mass dictates how much material there is to form the star, while its age influences the stage of its life cycle, which in turn affects its size.
Distance from Earth, size of star, and temperature of star.
Distance from Earth, size of star, and temperature of star.
the stars amount of mass
it depends on the star. size can determine "lifespan", and other conditions as well.
Three physical factors that determine a star's brightness are its temperature (hotter stars are brighter), size (larger stars are generally brighter), and distance from Earth (the closer a star is, the brighter it appears).
distance from the sun and the age of the star
You can determine star of a star planet by its color also you can determine its temperature by its color by:Joshua R. Dapitillo thanks=)
The two main factors that determine the characteristics of a star are its mass and its age. The mass of a star determines its temperature, size, luminosity, and lifespan. A star's age affects its stage in its life cycle, such as whether it is a young, main-sequence star or an older red giant.
To determine a star's luminosity, one can measure its apparent brightness as seen from Earth and correct for distance. Using this information along with the star's surface temperature, one can apply the Stefan-Boltzmann law to calculate the star's luminosity. This process allows astronomers to compare the intrinsic brightness of stars regardless of their distance from Earth.
It isn't clear what you want to determine about the star.
The apparent magnitude of a star is dependent on the star's size, temperature and distance from where it is observed. An absolute magnitude is determined by the same three factors, but the distance is fixed at 10 parsecs.