How big is Jupiter?

Jupiter is the largest planet in the Solar System and the fifth planet from the Sun. It is about 140,000 kilometers (87,000 miles) across, 11 times as wide as Earth. That figure is its mean diameter, 139,822 kilometers, the width of a perfect sphere with the same volume as Jupiter.

Size

Jupiter is a gas giant with no solid surface, so its size is measured to a level in its atmosphere rather than to the ground. Astronomers use the height where the pressure is 1 bar, about the same as the air pressure at sea level on Earth.

Jupiter is also slightly flattened, like a ball squeezed from top and bottom. It is 142,984 kilometers (88,846 miles) wide at the equator but 133,708 kilometers (83,082 miles) from pole to pole. The difference, 9,276 kilometers, is about three-quarters of Earth's width. The width at the equator is known to within about 10 kilometers. Jupiter also has the shortest day of any planet: it spins once every 9.9 hours.

Size comparisons

Jupiter's volume is about 1,300 times Earth's.
Saturn, the next-largest planet, is 116,464 kilometers (72,367 miles) across on average. Jupiter is 1.2 times as wide.
The Sun is about 1.39 million kilometers (865,000 miles) across, so about 10 Jupiters side by side would stretch across it.
If Jupiter were shrunk to the size of a basketball 24 centimeters (9.4 inches) across, Earth would be a ball 2.2 centimeters (0.9 inches) across, about the size of a grape.

A planet made of gas

Jupiter is made mostly of hydrogen and helium, the same main ingredients as the Sun. Its stripes are cold, windy clouds of ammonia and water. Deep inside, the crushing pressure turns hydrogen gas into a liquid, which makes Jupiter's hydrogen ocean the largest ocean in the Solar System.

Jupiter has 318 times the mass of Earth. When the Solar System formed about 4.6 billion years ago, Jupiter took up most of the material left over after the Sun formed. Not counting the Sun, it ended up with more than twice as much material as all the other bodies in the Solar System combined. Even so, it did not grow massive enough to start shining like a star.

Moons

As of 2026, Jupiter has more than 90 known moons. The four largest, Io, Europa, Ganymede and Callisto, were first seen by the astronomer Galileo Galilei in 1610 through an early telescope. Ganymede is the largest moon in the Solar System, bigger even than the planet Mercury. Io is the most volcanically active body in the Solar System, and Europa may hide an ocean of liquid water under its icy crust.