Jupiter is the fifth planet from the Sun and the largest in the Solar System. Jupiter is much larger than Earth and considerably less dense: its volume is that of about 1,321 Earths, but it is only 318 times as massive. Size and Distance With a radius of 43,440. If it has a solid inner core at all, it's likely only about the size of Earth. Jupiter has a diameter of about 88,695 miles (142,800 kilometers) which is more than 11 times the diameter of Earth.