According to NASA, Earth's radius at the equator is 3,963 miles (6,378 kilometers), while the radius at the poles is 3,950 miles (6,356 km). Therefore, the diameter of Earth through its center is ...

(Added to the U.S.: 650 square miles.) By U.S. measurements the earth’s radius at the equator is 3,963⅓-miles. Too small, said Izotov; he calculated that in its thickest section the radius is ...