How big is Mars?

Mars is a small planet, larger than only Mercury and slightly more than half the size of Earth. Its equatorial radius measures 3,396 kilometers (2,110 miles), with a mean polar radius of 3,379 kilometers (2,100 miles). By comparison, Earth’s equatorial radius is 6,378 kilometers (3,963 miles).

The mass of Mars is only one-tenth of Earth’s mass, a difference that contributes to the smaller planet’s lower gravitational pull. Mars’s gravitational acceleration is about 3.72 meters (12.2 feet) per second per second at the surface, which means that objects on Mars weigh a little more than a third of their weight on Earth’s surface.

Mars has only 28 percent of the surface area of Earth. However, because more than two-thirds of Earth is covered by water, the land areas of the two planets are comparable.