`radius = 6378137.0`

6378137.0

The Equatorial Radius of the Earth is 6,378,137.0 meters according to the WGS-84 earth datum.  The data above is provided in meters.  However, this can be automatically converted into other length and distance units via the pull-down menu.

The Science

The Mean Equatorial Radius is the average radius from the center of the Earth to the surface of the Earth at the Equator.   Due to the spin of the Earth, there is a slighte equatorial bulge as a result of the centrifugal force outward from the spin to counter, albeit slighly, the Earth's gravity.  The Polar Radius is  20K meters less.

• 6,356,752.3  Polar Radius
• 6,378,137.0  Equatorial Radius

Enter these values into the Volume of an Oblate Spheroid calculator to compute the volume of the Earth.

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Earth Model Calculators

• Slant Range using Position Vectors
• Slant Range from Elevation Angle (α)
• Slant Range using Subtended Angle (β)
• Distance to Horizon
• Angle of Satellite Visibility
• Grazing Angle
• XYZ to Latitude, Longitude, Altitude
• Earth WGS-84 Equatorial radius in meters: 6378137.0 m
• Earth WGS-84 Polar radius in meters: 6356752.31424518 m 
• Earth Flattening Factor (WGS-84): 0.00335281066474748071984552861852
• Ellipse flattening factor: F = (Er - Pr)/Er  
• Geocentric to Geodetic Latitude
• Geodetic to Geocentric Latitude

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Oblate Spheroid Calculators and Data

• Earth WGS-84 Equatorial radius in meters: 6378137.0 m
• Earth WGS-84 Polar radius in meters: 6356752.31424518 m 
• Earth Flattening Factor (WGS-84): 0.00335281066474748071984552861852
• Ellipse flattening factor: F = (Er - Pr)/Er  
• Geocentric to Geodetic Latitude
• Geodetic to Geocentric Latitude
• Slant Range