How Big Is Mars? Size, Surface and Gravity Compared With Earth
Mars is about half the width of Earth, but its surface area almost equals all of Earth's dry land. The size of Mars, explained simply.
Mars is often called a small planet, and it is: its diameter is about 6,780 km, a bit more than half of Earth's 12,742 km. You could fit about six planets the size of Mars inside Earth by volume.
Small planet, big land
There is a twist. Mars has no oceans, so all of its surface is land. Its total area is about 144 million km², very close to the area of all Earth's continents put together (about 149 million km²).
In other words, if you wanted to explore Mars on foot, you would have about as much ground to cover as all the land on Earth.
Key numbers
| Mars | Earth | |
|---|---|---|
| Diameter | about 6,780 km | 12,742 km |
| Distance around the equator | about 21,300 km | 40,075 km |
| Surface gravity | 3.71 m/s² (38% of Earth's) | 9.81 m/s² |
| Length of a day | 24 h 39 min | 24 h |
| Length of a year | 687 Earth days | 365 days |
| Highest point | Olympus Mons, about 22 km | Everest, 8.8 km |
Big features on a small planet
Low gravity and no plate tectonics let Mars build features far larger than anything on Earth: Olympus Mons, a volcano about 22 km tall, Valles Marineris, a canyon about 4,000 km long, and Hellas Planitia, a basin over 7 km deep.
Feel the size yourself
Numbers are hard to picture. In Trawers everything is at real scale, so driving from one crater to the next takes real time, and the leaderboard shows how far players have managed to go.