  The binding energy parameter $\lambda$ plays a vital role in common envelope
evolution. Though it is well known that $\lambda$ takes different values for
stars with different masses and varies during stellar evolution, it has been
erroneously adopted as a constant in most of the population synthesis
calculations. We have systematically calculated the values of $\lambda$ for
stars of masses $1-60\,M_{\odot}$ by use of an updated stellar evolution code,
taking into account contribution from both gravitational energy and internal
energy to the binding energy of the envelope. We adopt the criterion for the
core-envelope boundary advocated by \citet{Ivanova2011}. A new kind of
$\lambda$ with the enthalpy prescription is also investigated. We present
fitting formulae for the calculated values of various kinds of $\lambda$, which
can be used in future population synthesis studies.
