Quick answer: Jupiter has a mass of approximately 1.898 × 1027 kilograms—about 318 times Earth’s mass. It is the most massive planet in our solar system, containing more than twice as much mass as all the other planets combined. Yet Jupiter is made mainly of hydrogen and helium, so its average density is much lower than Earth’s.
How much does Jupiter weigh?
In everyday speech, people ask how much Jupiter weighs. Scientists generally use mass for this comparison, because weight depends on the local gravitational field. Jupiter’s mass is about 1.898 septillion metric tons, or approximately 1.898 × 1027 kilograms. The exact digits vary slightly depending on the reference values and rounding convention.
Mass measures the amount of matter in a body and determines much of its gravitational influence. Jupiter’s huge mass affects the motion of its moons, nearby small bodies and other objects throughout the solar system.
Jupiter’s mass compared with other planets
| Planet | Approximate mass relative to Earth |
|---|---|
| Earth | 1 Earth mass |
| Jupiter | 318 Earth masses |
| Saturn | 95 Earth masses |
| Neptune | 17 Earth masses |
| Uranus | 14.5 Earth masses |
Jupiter is about 3.3 times as massive as Saturn. That makes Jupiter by far the dominant planet in terms of mass, though the Sun is enormously more massive than every planet combined.
Why is Jupiter so massive?
Jupiter formed early in the solar system’s history and accumulated a huge envelope of hydrogen and helium. Planet-formation models suggest that a growing core and surrounding gas could draw material from the young Sun’s protoplanetary disk. The details of when and how Jupiter formed remain active research questions.
Because Jupiter is composed largely of light elements, its average density is only about 1.33 grams per cubic centimeter. Earth, made primarily of rock and metal, averages about 5.51 grams per cubic centimeter. A planet can therefore have enormous mass without having Earth’s dense, rocky composition.
How does Jupiter’s mass affect gravity?
At the conventional one-bar atmospheric level, Jupiter’s gravitational acceleration is roughly 24.8 meters per second squared, compared with Earth’s 9.8 meters per second squared. That is about 2.5 times Earth’s surface gravity. This figure describes a reference atmospheric level, not a solid surface where someone could stand.
Jupiter’s strong gravity helps hold its extensive system of moons and influences the trajectories of comets and asteroids. Some objects can be redirected, captured or ejected during encounters with the planet.
Is Jupiter almost a star?
Jupiter is sometimes called a failed star, but that description is misleading. Its mass is nowhere near enough to sustain hydrogen fusion in its core like the Sun. Jupiter would need to be vastly more massive to approach the conditions of an ordinary hydrogen-burning star.
Objects called brown dwarfs occupy a different mass regime between planets and stars, although their classification involves formation and other considerations as well. Jupiter remains a planet: a gas giant that does not generate energy through sustained hydrogen fusion.
How do scientists measure Jupiter’s mass?
Scientists measure Jupiter’s gravitational effect on orbiting objects and passing spacecraft. The motions of its moons, along with precise radio tracking of spacecraft, allow researchers to estimate the planet’s gravitational parameter. Combining that parameter with the gravitational constant gives an estimate of mass.
NASA’s Juno mission has also helped refine knowledge of Jupiter’s gravity field and internal mass distribution. That is different from simply weighing the planet on a scale: it uses the predictable relationship between gravity and motion.
Why does Jupiter’s size not tell the whole story?
Jupiter’s diameter is about 11 times Earth’s, while its mass is about 318 times Earth’s. Those numbers do not scale in the same way because volume grows with the cube of radius and because planets have different densities and internal compression. Gas giants can become denser under their own gravity, so adding mass does not always produce a proportionate increase in radius.
Frequently asked questions
How many Earths equal Jupiter’s mass?
About 318 Earth masses equal Jupiter’s mass. This is a mass comparison, not a claim that 318 Earth-sized spheres would fill its volume.
Is Jupiter heavier than all the other planets combined?
Yes. Jupiter’s mass exceeds the combined mass of the other seven planets by more than a factor of two.
How much stronger is Jupiter’s gravity than Earth’s?
At the commonly used one-bar atmospheric reference level, gravity is about 2.5 times Earth’s surface gravity.
Could Jupiter turn into a star?
Not at its present mass. It lacks the mass required for sustained hydrogen fusion.
Bottom line
Jupiter’s mass is a defining feature of the solar system. It is 318 times Earth’s mass and dominates planetary gravitational interactions, but its hydrogen-rich composition and lack of a solid surface make it very different from a giant rocky world.
References: NASA Jupiter facts; NASA Juno mission.
