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12,742 km
Preparing the solar system
PLANET SIZE GUIDE

Planet Size Comparison: Orbits, Scale & Mass

The solar system changes character depending on what you measure. Follow a planet in Orbit, line up real diameters in Compare, or put seemingly similar worlds on the Mass balance. Each view answers a different question, and together they make the scale of our neighborhood much easier to feel.

HOW TO COMPARE

How this planet size comparison works

Solar-system pictures usually cheat a little. If the distances were fully accurate, the planets would become tiny points. If the planet sizes were fully accurate, the space between them would be difficult to show.

For size, the page uses equivalent-volume mean diameter: the diameter of a sphere with the same volume as the body. This keeps round and slightly flattened worlds on one consistent measure. Saturn’s rings are shown in the artwork, but they do not count toward Saturn’s diameter.

So when two views appear to disagree, pause before assuming one is wrong. Orbit protects context. Compare protects diameter. Mass reveals how much matter is packed into a body. The interesting part begins where those answers stop matching our intuition.

THREE WAYS TO EXPLORE

Choose the view that fits your question

You do not need to learn every control before starting. Pick a mode, choose a world that catches your eye, and follow the next question. The three views are designed to hand off naturally from one kind of curiosity to another.

Orbit — see where a world belongs

Start here when you want the solar system as a place rather than a list. Drag to change your viewing angle, scroll or pinch to zoom, then select a planet. Track keeps the camera with that world while the system moves; Inspect brings it close without losing your selection. Turn on orbits and names when you need orientation. Accurate sizes and real distances are available when you want the honest scale, but expect the scene to become sparse—that emptiness is part of the answer.

Best for: motion, position, moons, and the relationship between a planet and its orbit.

Compare — put every diameter on one baseline

Use Compare when the simple question is “how big?” Every body stands on the same baseline, so a planet twice as wide really appears twice as wide. Zoom for the rocky planets, use Fit to bring the full selection back into view, and switch on Spacing when labels begin to crowd each other. The body selector lets you add the Sun, Pluto, or moons without pretending they all belong to the same category.

Best for: true diameter, size order, and close pairs such as Earth and Venus or Uranus and Neptune.

Mass — discover when size is misleading

Mass turns comparison into a balance experiment. Add a body to either pan, change its quantity, or ask the tool to match the opposite side automatically. Try one Jupiter against Earths, then compare the Moon with a smaller world. The beam makes the difference visible, while the totals show the real calculation. A wide planet is not always the heavier one, so this view often produces the most surprising result.

Best for: “how many would it take?” questions and for separating physical width from total mass.

Planet sizes compared by mean diameter and relative to Earth
PlanetMean diameterEarth = 1Size rank
Mercury4,878.8 km0.38×8
Venus12,103.6 km0.95×6
Earth12,742 km1.00×5
Mars6,779 km0.53×7
Jupiter139,822 km11.0×1
Saturn116,464 km9.14×2
Uranus50,724 km3.98×3
Neptune49,244 km3.86×4

Planet sizes compared to Earth

The table gives the order; these short profiles explain the moments worth noticing. Look for the near-tie between Earth and Venus, the small gap between the ice giants, and the enormous jump from the rocky planets to Jupiter and Saturn.

Jupiter size: the largest planet

Jupiter sets the upper end of the planet lineup. Its mean diameter is 139,822 km, about 11 Earths across. It is enormous beside every other planet, yet still only about one tenth of the Sun’s diameter.

Saturn size without the rings

Saturn size is measured across the globe, not across its ring system. Its mean diameter is 116,464 km, or about 9.14 Earth diameters. The rings appear wider, but they are not included in Saturn’s measured size.

Uranus size and the ice giants

Uranus is 50,724 km wide, or 3.98 Earth diameters. It narrowly takes third place ahead of Neptune. Many illustrations make the two ice giants look identical, so this close pairing is easier to notice on a shared scale.

Neptune size compared with Uranus

Neptune measures 49,244 km in mean diameter, about 3.86 Earths across. It is slightly narrower than Uranus but more massive—a useful reminder that width and mass do not tell the same story.

Earth size as the comparison baseline

Earth is the page’s familiar baseline. Its mean diameter is about 12,742 km, shown as 1.00×. From there, Venus is nearly one Earth wide, Mars just over half, and Jupiter almost eleven.

Venus size compared with Earth

Venus is 12,103.6 km wide, approximately 0.95 Earth diameters. It is the closest planet to Earth in physical size, so the two should look almost equal in Compare mode. Only about 638 km separates their diameters.

Mars size compared with Earth

Mars has a mean diameter of 6,779 km, about 0.53 Earth diameters. It is only a little more than half as wide as Earth, even though orbital diagrams often enlarge it enough to stay visible.

Mercury size: the smallest planet

Mercury is the smallest planet, with a mean diameter of 4,878.8 km—about 0.38 Earth diameters. It is wider than Earth’s Moon but smaller than Ganymede and Titan.

INNER SOLAR SYSTEM

Rocky planet size comparison

Earth and Venus almost form a matched pair: Venus is about 95% of Earth’s diameter. Then the scale drops sharply. Mars is about 53% of Earth’s width and Mercury about 38%. All four have solid surfaces, yet the group stretches from 4,878.8 km for Mercury to about 12,742 km for Earth.

OUTER SOLAR SYSTEM

Giant planet size comparison

Jupiter and Saturn are gas giants; Uranus and Neptune are ice giants. Even Neptune, the narrowest of the four, is almost four Earths across. That sudden jump after Earth is one of the chart’s strongest moments: the outer planets do not merely edge past the rocky worlds. They change the scale of the picture.

STAR-SCALE REFERENCE

Use the Sun as a separate scale reference

The Sun can be added separately in Compare. Its nominal photospheric diameter is 1,391,400 km, about 109 times Earth’s diameter and almost ten times Jupiter’s. That scale is useful for perspective, but it also overwhelms a normal planet lineup.

For a clear comparison, keep like with like: compare planets with planets, and moons with bodies of a similar size. Avoid putting the Sun and small moons in the same view; the diameter gap is too large for both ends to remain readable. Add the Sun briefly when you want the star-scale reference, then remove it to continue inspecting the smaller worlds.

QUICK ANSWERS

Planet size questions

What is the largest planet in the solar system?

Jupiter is the largest planet in the solar system. Its mean diameter is about 139,822 km, or roughly 11 times Earth’s diameter. Jupiter is followed by Saturn, Uranus, and Neptune.

What is the planet size order from largest to smallest?

The planet size order is Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, and Mercury. This order uses equivalent-volume mean diameter, not mass or ring width.

How do Earth, Venus, and Mars compare in size?

Earth size is 12,742 km in this comparison. Venus size is close at 12,103.6 km, or about 95% of Earth’s diameter. Mars size is 6,779 km, about 53% of Earth’s diameter. Venus therefore looks almost equal to Earth, while Mars appears a little more than half as wide.

Is the Sun included in the planet size comparison?

The Sun is available as an optional scale reference rather than a planet in the ranked lineup. Add it separately in Compare when you want to see star-to-planet scale. For a readable chart, avoid combining the Sun with small moons in the same view; the diameter gap is so large that the smaller bodies collapse into dots.

How large is Pluto compared with the planets?

Pluto size is about 2,376.6 km in diameter. Pluto is smaller than Mercury and smaller than Earth’s Moon. It is classified as a dwarf planet, so you can add it to the interactive planet size comparison without treating it as one of the eight planets.

Which planet is closest to Earth size?

Venus is closest to Earth size. Venus has about 95% of Earth’s diameter, while Mars has about 53%. Earth is only about 638 km wider than Venus, which is why the two planets look nearly equal in a true-scale planet size comparison chart.

Do Saturn’s rings count toward Saturn size?

No. Saturn size means the mean diameter of its atmospheric globe. The artwork shows the rings, but the measurement does not include them.

Why do small planets look tiny in true scale?

A true-scale planet size chart preserves the real diameter ratio. Jupiter is nearly 29 times wider than Mercury, and the Sun is about 285 times wider than Mercury. When all bodies share one scale, rocky planets must look small. Use zoom and drag to inspect them without changing the underlying ratio.