How big is Saturn?

Updated October 19, 2026 · 5 min read

Saturn is about 120,536 km (74,900 miles) wide at the equator, roughly 9.5 times the diameter of Earth, which makes it the second-largest planet after Jupiter. Its volume could hold about 764 Earths, but its mass is only 95 times Earth's, because the planet is made mostly of hydrogen and helium. It is also noticeably squashed: from pole to pole it measures about 108,700 km.

Saturn's diameter and radius

Because Saturn has no solid surface, its size is measured at a reference pressure level, conventionally 1 bar, the same as sea-level pressure on Earth. At that level the equatorial radius is 60,268 km and the polar radius 54,364 km. These values come mainly from radio occultations, in which spacecraft signals grazing the planet are bent and cut off by the atmosphere, revealing where a given pressure lies.

Doubling the radius gives an equatorial diameter of 120,536 km and a polar diameter of about 108,700 km. Lined up along the equator, about nine and a half Earths would fit edge to edge across Saturn's disk, not counting the rings. Including the main rings, which extend to about 140,000 km from the center, the whole system spans some 280,000 km, roughly three quarters of the distance between Earth and the Moon.

The flattest planet

Saturn's oblateness, or flattening, is about 0.098: the polar radius is almost 10% smaller than the equatorial one. No other planet is as squashed. Jupiter's flattening is about 0.065 and Earth's only 0.0034.

Two factors combine. First, Saturn rotates in about 10 hours 33 minutes, so material at the equator moves at roughly 36,000 km/h, and the resulting centrifugal effect makes the equator bulge. Second, Saturn's low density and weak internal binding mean it yields more to that effect than a denser planet would. The difference between the equatorial and polar diameters, nearly 12,000 km, is almost the full width of the Earth. In good telescope views or Cassini images, the oval outline is visible at a glance. Details on the spin are on the day length page.

Mass: 95 Earths

Saturn's mass is about 5.683 × 10²⁶ kg, or 95.2 times Earth's. It is measured from the orbits of its moons and, more precisely, from the tracking of spacecraft: tiny shifts in Cassini's radio frequency during its 2017 Grand Finale orbits gave the most detailed map of Saturn's gravity field ever obtained.

To put that mass in context:

• Jupiter is about 3.3 times more massive than Saturn.
• Saturn contains about a fifth of the mass of all the planets combined; Jupiter holds more than two thirds.
• The Sun is about 3,500 times more massive than Saturn.
• Saturn's rings, impressive as they look, weigh about 1.5 × 10¹⁹ kg, some 40 million times less than the planet.

Most of that mass is hydrogen and helium. Heavier elements, rock and ices, account for perhaps 15 to 20 Earth masses, concentrated toward the center in a diffuse core described on the interior page.

Volume and density

Saturn's volume is about 8.3 × 10¹⁴ km³, around 764 times Earth's. Divide its mass by that volume and you get a mean density of 0.687 g/cm³, lower than that of liquid water (1 g/cm³) and the lowest of any planet. Earth, by comparison, averages 5.51 g/cm³.

This is not because Saturn is made of something unusually light throughout. Its interior is highly compressed; the deep layers are far denser than water. It is the enormous, puffy hydrogen envelope that brings the average down. The page on density and the floating myth goes further.

Comparing Saturn with other bodies

Saturn is about 84% as wide as Jupiter but has less than a third of its mass. That contrast is a consequence of physics: adding mass to a hydrogen planet compresses it, so above a certain point giant planets barely grow in size as they gain mass. The full comparison is on the Saturn vs Jupiter page, and our own planet is put to scale in Saturn vs Earth.

Surface area and gravity

Saturn's area at the 1-bar level is about 83 times Earth's. Despite its huge mass, the gravity at that level on the equator is only about 10.44 m/s², or 1.07 g, because the cloud tops lie so far from the center. Near the poles, closer to the center and without the centrifugal effect, gravity is noticeably stronger, roughly 12 to 13 m/s². The gravity and weight page includes a calculator.

Sources

• NASA NSSDCA: Saturn Fact Sheet
• NASA Science: Saturn facts
• Iess, L. et al. (2019), "Measurement and implications of Saturn's gravity field and ring mass", Science 364
• Lindal, G. F. et al. (1985), "The atmosphere of Saturn: an analysis of the Voyager radio occultation measurements", The Astronomical Journal 90