Earth Radius | Rotational Circumference | Distance to Equator and Pole | Earth's Curvature | Time Difference
Calculator for the Earth's Curvature
Uses the Earth's radius to calculate the length of a line on Earth, the direct distance through the Earth, and the curvature of the Earth through the height of the center of the track above the direct line. For the formulas used for the calculation, see circular segment. The average value of 6371 kilometers is preset as the earth's radius. Please enter another value to calculate the other three values.
Example: for a distance on earth of 100 kilometers, the direct distance is only slightly less. If you'd dig straight through the earth, you would save about one meter of distance and would be at the deepest point about 196 meters below the surface.
This calculation is not entirely correct, as the Earth is not a perfect sphere. Its shape is that of a flattened spheroid, so its cross-section is an ellipse. To calculate the direct distance, you would need the length of the chord in an elliptical segment, which cannot be calculated algebraically. However, the shape of the Earth is not strongly elliptical; its radius at the equator is 6378 kilometers, and at the poles it is 6357 kilometers. The radius at a specific location can be calculated using Earth's radius based on latitude. If the two endpoints at which measurements are to be taken are far apart in a north-south direction, you can simply take the average of the two radii at these points and thus obtain a good approximation.
It is more difficult to take into account that the Earth has dents and bumps due to a non-homogeneous density distribution. However, these are in the range of ±100 meters, so they are very small compared to the Earth. Then of course there are mountains and valleys, which can be taken into account by including the height above or below sea level in the radius.
Last updated on 06/30/2025. Author: Jürgen Kummer
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