Mars is a small, rocky planet a bit over half the size of Earth by diameter.

Quick Scoop: Size of Mars

  • Diameter: About 6,790–6,800 km at the equator (roughly half Earth’s diameter of about 12,700 km).
  • Radius: About 3,390 km from the center to the surface.
  • Surface area: Around 145 million square kilometers, which is fun because that’s similar to the total land area of Earth.
  • Volume: A bit over 15% of Earth’s volume, so you could fit several Mars-sized planets inside Earth.

If you imagine Earth as a full-size basketball, Mars would be closer to a medium-sized grapefruit sitting next to it.