What is Saturn mostly made of?

Saturn is primarily composed of hydrogen, which makes up the vast majority of its bulk mass. Because of the extreme pressures within the planet, this hydrogen exists mostly as a liquid rather than a gas.12

The planet’s composition also includes significant amounts of helium, though it is less abundant relative to hydrogen than in the Sun. In addition to these primary elements, Saturn contains a dense central core likely composed of a mixture of rock and ice, estimated to be approximately 15–18 times the mass of Earth.32

Deeper within the planet, at pressures exceeding two megabars, the fluid hydrogen is predicted to transition into a metallic state. The presence of these heavier materials—denser than hydrogen—is concentrated toward the planet's center, contributing to Saturn's overall structure and gravitational field.2