The diameter of the Earth is 7,926 miles at the equator; however, if the diameter of the Earth is measured through the North and South Poles, the diameter is only 7,901 miles. This length is slightly shorter than the width.
Although the Earth has a sphere-like shape, the rotation of the Earth has caused the planet to flatten out slightly. For that reason, the Earth has a larger diameter at the equator. The diameter of the Earth varies as a result of a tiny bulge located at the equator. This bulge is called an ellipsoid or, more accurately, a geoid.