How big is Mars compared to Earth?
53%of Earth’s width
Mars is 53% of Earth’s width — 6,779 km across against Earth’s 12,742 km. By volume, Earth could hold about 7 of them. It has about 11% of Earth’s mass, and its surface gravity is 0.38× Earth’s.
▶ See Mars next to Earth in 3D
Side by side
Width vs Earth
53% of Earth’s
Volume vs Earth
15% of Earth’s
Mass vs Earth
about 11% of Earth’s mass
Surface gravity
0.38× Earth (3.7 m/s²)
You’d weigh
26 kg (if 70 kg here)
Diameter
6,779 km
Mars is small enough that roughly 7 of them would fit inside Earth.
What that actually feels like
Mars is the most explored planet beyond Earth, and the most Earth-like in rhythm: its day is only 39 minutes longer than ours and it has seasons, ice caps and weather. But its air is less than 1% as thick as Earth’s and mostly CO₂. Billions of years ago rivers ran here — the dry valleys and lake beds our rovers drive through are the evidence.
Ratios on a page are easy to nod along to and impossible to picture. In the interactive view, switch to True scale to see Mars and Earth at their honest relative sizes.
Keep going
✓ Facts verified July 2026
Every figure on this page is a real, rounded value checked against primary sources. Found something out of date? See how we keep it accurate.