**Einstein's radius of universe**, usually denoted in cosmology by , is the radius of curvature of space of Einstein's universe.

The exact length of **Einstein's radius of universe** is , where is speed of light in vavcuum, is Newtonian gravitational constant, and is density of space.

Assuming that we live in stationary (neither expanding nor contracting) Einstein's universe in which the Hubble constant is ca. as established by observations, the **Einstein's radius of universe** is ca. 13 bilion light years. The exact number is then .