Earth Radius by Latitude Calculator
Earth isn't a perfect sphere, but is oblate at its poles, due to its rotation. Therefore, the Earth radius isn't constant, but it can be calculated for every location. For this calculation, the longitude isn't needed. Mathematically, Earth is a spheroid.
Earth radius at sea level is 6378.137 km (3963.191 mi) at the equator. It is 6356.752 km (3949.903 mi) at the poles and 6371.001 km (3958.756 mi) on average. The height above sea level of the location is added. Please enter the latitude in decimal degrees, here you can convert coordinates.
Formula for the calculation
latitude B, radius R, radius at equator r1, radius at pole r2
R = √ [ (r1² * cos(B))² + (r2² * sin(B))² ] / [ (r1 * cos(B))² + (r2 * sin(B))² ]
Height above sea level can be negative, then you are below sea level.