Approximately how many Earths could fit inside the Sun by volume?

Approximately 1.3 million Earths could fit inside the Sun by volume. This comparison comes from dividing the Sun’s volume by Earth’s volume, not from comparing their diameters. The Sun is about 109 times wider than Earth, and volume increases with the cube of a sphere’s radius, producing a much larger difference in capacity.

The Sun’s enormous size reflects its role as the central star of the Solar System. It contains about 99.86 percent of the Solar System’s total mass, with the planets, moons, asteroids, and comets making up most of the remainder. Even though the Sun is vastly larger than Earth, it is still considered an ordinary-sized star compared with many giant and supergiant stars.

The figure is an approximate geometric comparison. Real Earth-sized spheres cannot be packed perfectly without leaving gaps, so “1.3 million Earths” refers to the ratio of volumes. If one imagined physically packing spheres, the usable count would be somewhat lower because of empty space between them.

The Sun’s diameter is roughly 1.39 million kilometres, while Earth’s diameter is about 12,742 kilometres. Its immense volume also helps explain why the Sun’s gravity dominates the motions of the planets.