On average, how many stars does a galaxy have?

The average number of stars in a galaxy is typically estimated to be around 100 billion. This figure is based on a variety of observations and studies of different sizes and types of galaxies. While some smaller dwarf galaxies can have as few as a billion stars, larger spiral galaxies and elliptical galaxies often possess hundreds of billions of stars. This understanding is informed by substantial astronomical research, including deep-sky surveys and modeling of galaxy formation and evolution.

The estimation of 100 billion stars allows for a more accurate reflection of an average galaxy's star count, considering that our Milky Way alone harbors approximately 100 to 400 billion stars. Therefore, while the figure of 40 billion might seem plausible, it underestimates the average count across the variety of galaxies observed in the universe. The choice of 100 billion is well-supported by the current astronomical consensus.