Planet Size Comparison Tool

Quick Answer

How big is Jupiter compared to Earth?

Jupiter is 11.21× Earth’s diameter (142,984 km (88,846 mi) vs 12,756 km (7,926 mi)) and about 1,408 Earth volumes in a sphere model.

Which planet is closest in size to Earth?

Venus. Venus is about 94.9% of Earth’s diameter.

Is Mars bigger than Earth?

No. Mars is smaller — about 53.2% of Earth’s diameter (6,792 km (4,220 mi) vs 12,756 km (7,926 mi)).

What is the largest planet?

Jupiter is the largest of the eight official planets. Saturn is next (9.45× Earth’s diameter).

What is the smallest planet?

Mercury is the smallest official planet. Pluto is a dwarf planet and is smaller than the Moon (3,474.8 km (2,159.1 mi)).

Popular Planet Size Comparisons

These write-ups use the same diameters as the interactive planet size comparison tool. Open any pair to see radius, volume, and mass side by side.

Planet Size Chart

Mean equatorial diameter, sphere-model volume, mass in Earth units, and surface gravity from the same NASA-style table. Pluto’s mass is 0.0025 M⊕ — not zero.

Planets by Size

Among the eight official planets, the diameter order is Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury. Jupiter is clearly the largest. Mercury is clearly the smallest. Pluto is a dwarf planet and is not counted in that list. The Sun is a star (109.18× Earth’s diameter). The Moon is a natural satellite and is wider than Pluto.

1. Jupiter — 142,984 km (88,846 mi)
2. Saturn — 120,536 km (74,898 mi)
3. Uranus — 51,118 km (31,763 mi)
4. Neptune — 49,528 km (30,775 mi)
5. Earth — 12,756 km (7,926 mi)
6. Venus — 12,104 km (7,521 mi)
7. Mars — 6,792 km (4,220 mi)
8. Mercury — 4,879 km (3,032 mi)

How Planet Size Is Compared

This planet size comparison uses mean equatorial diameter as the primary size. Radius is half that diameter. Mass is a separate quantity: a world can be similar in width and still differ in mass, as Uranus and Neptune do. Physical size is not the same as distance from the Sun.

• Diameter — width through the equator, in kilometers or miles.
• Radius — half the diameter.
• Volume — sphere model from that radius.
• Mass — Earth-mass units from the same fact-sheet table.
• Earth-relative ratios — each value divided by Earth’s matching value.

Gas-giant diameters are measurement- and model-dependent (often a 1-bar reference). Treat them as educational values, not engineering tolerances.

Formula and Methodology

Diameter ratio = Planet A diameter ÷ Planet B diameter.

Volume uses a sphere: V = 4/3 × π × r³. Because r is cubed, a planet that is only about 10× wider can have more than 1,000× the volume. Jupiter is 11.21× Earth’s width, so its sphere-model volume is about 1,408 Earth volumes.

The page does not claim that Earths can be stacked inside Jupiter like marbles. Sphere volume is a teaching model. Real interiors are compressed, oblate, and — for giants — gaseous.

Real Examples

• Earth vs Jupiter: Earth is about 8.9% of Jupiter's diameter. Open Earth vs Jupiter.
• Earth vs Sun: Earth is about 0.9% of Sun's diameter. Use Fit comparison if the true-scale Earth circle is too small to see.
• Earth vs Moon: Earth is 3.67× wider than Moon.
• Uranus vs Neptune: Uranus is 1.03× wider than Neptune. Mass tells a different story.

Common Planet Size Comparison Mistakes

1. Confusing planet size with orbital distance. Width is not AU. Use the Planet Distance Converter for mean Sun–planet spacing.
2. Confusing diameter with volume. A modest width ratio becomes a huge volume ratio because volume uses r³.
3. Counting Saturn’s rings as planet diameter. Rings are a disk around Saturn, not the globe itself.
4. Assuming every world has a hard solid surface. Jupiter and Saturn are gas giants; published diameters are reference levels.
5. Treating Pluto as one of the eight planets. Pluto is a dwarf planet in this chart.
6. Assuming a picture is automatically to scale. This tool labels True scale versus Fit comparison so a drawing is never mistaken for a hidden ratio change.

Frequently Asked Questions

What does a planet size comparison show?

It shows how two worlds compare in physical size: mean equatorial diameter, radius, sphere-model volume, and mass. It does not show how far a planet orbits from the Sun.

How big is Jupiter compared to Earth?

Jupiter’s mean equatorial diameter is 142,984 km versus Earth’s 12,756 km, so Jupiter is 11.21× wider. In a sphere model that is about 1,408 Earth volumes.

How many Earth volumes is Jupiter?

Using V = 4/3 × π × r³ and the same diameters as this page, Jupiter has about 1,408 Earth volumes. That is a geometry model, not a claim that Earths can be packed inside Jupiter.

Is Mars bigger than Earth?

No. Mars is about 6,792 km across, roughly 53% of Earth’s diameter, with far less volume and mass.

Which planet is closest in size to Earth?

Venus. Its mean diameter is 12,104 km, about 94.9% of Earth’s width — a near match in scale, not in atmosphere or surface.

What is the largest planet?

Jupiter is the largest official planet in the Solar System by diameter and by mass. Saturn is second in diameter.

What is the smallest planet?

Mercury is the smallest of the eight official planets. Pluto is a dwarf planet and is smaller than Earth’s Moon.

Is Venus almost the same size as Earth?

Venus is the closest official match, but it is still smaller: 12,104 km versus 12,756 km, about 94.9% of Earth’s diameter.

Is Uranus bigger than Neptune?

Uranus is slightly wider (51,118 km vs 49,528 km). Neptune is more massive. Ice-giant diameters are close and measurement-dependent.

Is Pluto a planet?

Pluto is classified as a dwarf planet. This tool includes it for scale, but it is not one of the eight official planets.

Does the tool use real planetary data?

Yes. Diameters, masses, and gravities follow NASA Planetary Fact Sheet style educational values. Gas-giant widths are reference levels, not solid surfaces.

Are comparisons processed in the browser?

Yes. Planet picks and ratios are calculated on your device. EverydayTools does not need those selections uploaded to a server.

Related Tools

Size is only one measurement. Check Weight on Other Planets for surface gravity, Age on Other Planets for orbital years, the Planetary Day Converter for rotation length, and the Planetary Year Converter for year length. Use the Planet Distance Converter when the question is orbital spacing, not globe width.

• Weight on Other Planets — Turn the same NASA-style dataset into surface gravity at your mass.
• Age on Other Planets — Convert a birth date into orbital years on each world.
• Planet Distance Converter — Compare mean distances from the Sun — size is not the same as orbital distance.
• Planetary Day Converter — See how long a rotation lasts on Mars, Jupiter, and other worlds.
• Planetary Year Converter — Compare orbital-year lengths, which are independent of planet diameter.