The Earth's mean radius is determined as the average distance from the physical center to the surface, based on a large number of samples. The value, symbolized *r*_{earth}, is equal to approximately 6,371,000 meters (6.371 x 10^{6} m). This is roughly 6,371 kilometers (km) or 3,960 statute miles.

The Earth is slightly oblate, so its radius in the plane of the equator is a little larger than its radius along the rotational axis. In addition, there are irregularities in the surface because of hills, mountains, tides, and rainfall.

Based on the value of *r*_{earth} given here, the volume of the planet (*V*_{earth}), in meters cubed (m^{3}), can be found using the standard formula for the volume *V* of a sphere in terms of its radius *r*:

*V* = (4/3)(pi) *r*^{3}

where pi represents the ratio of the circumference of a circle to its diameter, an irrational number equal to approximately 3.14159. Based on this formula:

*V*_{earth} = 1.083 x 10^{21} m^{3}

Also see Table of Physical Units and Constants.

*This was last updated in*September 2005

*Posted by:*Margaret Rouse

## Tech TalkComment

## Share

## Comments

## Results

## Contribute to the conversation