Correspondence Principle

$epsilon = v ^2/(2*c^2)$

Enter a value for all fields

The Correspondence Principle requires that $gamma$ be close to 1 for the velocities much less than $c$ encountered in everyday life. It is found using the following formula: $epsilon=v^2/(2c^2)$ , where:

$epsilon$ = amount by which $gamma$ differs from 1, when $v$ is small
$v$ = relative velocity of two observers
$c$ = universal velocity that is the same in all frames of reference (speed of light)

References

23.1 Relativistic distortion of space and time by Benjamin Crowell, Light and Matter licensed under the Creative Commons Attribution-ShareAlike license.