Mars has an oblate spheroid shape, which means that its polar and equatorial diameters are different. At the equator, Mars has a diameter of 4,222 miles (6,794 km), while from pole to pole, the diameter is 4,196 miles (6,752 km) . Its radius is half of its diameter, which is 2,111 miles at the equator and 2,098 miles from pole to pole. The circumference of Mars around the equator is about 13,300 miles (21,343 km), but from pole-to-pole, Mars is only 13,200 miles (21,244 km) around.