The planet with the largest volume is Jupiter. Jupiter is a gas giant and is the fifth planet from the Sun and the largest in the Solar System. It is composed mostly of hydrogen and helium, and its mass is about 318 times that of Earth. Jupiter has a diameter of about 142,984 kilometers, and its volume is approximately 1.43 x 10^15 cubic kilometers, which is about 1,321 times the volume of Earth.