How much wider is Earth at the equator than it is at the poles?

Earth's equatorial diameter is about 12,756 kilometers (7,926 miles), while its polar diameter is approximately 12,714 kilometers (7,900 miles). This results in a difference of about 42 kilometers (26 miles), meaning Earth is wider at the equator than at the poles due to its oblate spheroid shape. This bulging at the equator is primarily caused by the planet's rotation.