Mars
Mars is a rocky planet orbiting the Sun, with a reddish surface due to iron oxide.
How big is it?
6,779 km across
Mean diameter · approximate
A little perspective
About 1.29 times the mean diameter of Ganymede.
Ganymede: Ganymede is a natural satellite of Jupiter and contains a magnetic field generated by its partially liquid core.
Measurements, assumptions & sources +
Mars
Mean-radius spherical model for Mars; actual shape is not perfectly spherical.
NASA JPL — planetary physical parameters
The marked mean diameter is calibrated. Unmeasured illustration details are representative.
Ganymede
Rounded mean-radius model of Ganymede. The derived area and volume describe a sphere; surface terrain and flattening are omitted.
NASA JPL — Planetary satellite physical parameters
The marked mean diameter is calibrated. Unmeasured illustration details are representative.
Change your perspective
Put it next to…
Choose a suggestion to redraw the comparison, or open its page to learn what it is.
Why this measurement?
Why we use 6,779 km
For comparison, this page uses mean diameter. This is labelled approximate; the central value is useful for comparison, while real values or measurement solutions can vary.
Mean-radius spherical model for Mars; actual shape is not perfectly spherical.
The marked horizontal span follows the named feature; transparent margins and unmeasured details do not alter it. How calibrated comparisons work →
Recorded properties
Mars dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 6,779 km | Not recorded | approximate | |
| 3,390 km | Not recorded | approximate | |
| 21,300 km | Not recorded | derived | |
| 144,400,000 km² | Not recorded | derived | |
| 1.631 × 10¹¹ km³ | Not recorded | derived | |
| 6.417 × 10²⁰ t | Not recorded | approximate | |
| 3.71 m/s² | Not recorded | approximate | |
| 1.524 AU | Not recorded | rounded orbital anchor | |
| 86,650 km/h | Not recorded | rounded orbital anchor |
Around this scale
Go smaller. Go bigger.
These links use compatible length records, ordered around the selected value.
Nearest lower value · PlacesNile6,650 kmThe Nile is a prominent river in northeastern Africa, flowing northward through several countries before reaching the Mediterranean Sea.Around the same scale · PlacesAmazon River6,400 kmThe Amazon River is a major waterway in South America that flows eastward across the continent and drains a vast rainforest basin.
Nearest higher value · SpaceEarth12,740 kmEarth is the rocky planet on which we live and the third planet from the Sun.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- NASA JPL — planetary physical parametersMean radii and masses. Spherical area and volume here are derived from mean radius. This atlas rounds for scale comparison.
- NASA — Planet CompareConventional surface gravities; giant-planet values refer to an atmospheric reference level. Earth uses standard gravity, 9.80665 m/s².
- Defined examples — our methodology
More ways to see it
Curated comparisons
There’s always another scale
Follow your curiosity.
SpaceEarth12,740 kmEarth is the rocky planet on which we live and the third planet from the Sun.
SpaceMoon3,475 kmThe Moon is Earth’s natural satellite and the brightest large object in Earth’s night sky.
SpaceJupiter139,800 kmJupiter is a giant planet composed mainly of hydrogen and helium, orbiting the Sun beyond the asteroid belt.
SpaceSun1,391,000 kmThe Sun is the star at the centre of the Solar System.
SpaceGanymede5,262 kmGanymede is a natural satellite of Jupiter and contains a magnetic field generated by its partially liquid core.
SpaceTitan5,150 kmTitan is a natural satellite of Saturn, with a thick nitrogen-rich atmosphere and surface lakes of hydrocarbons.
SpaceMercury4,879 kmMercury is a rocky planet orbiting closest to the Sun in the Solar System.
SpaceCallisto4,821 kmCallisto is a natural satellite of Jupiter, with a heavily cratered icy surface.