Tiêu chuẩn Grashoff được tính theo công thức:

\[{\rm{Gr = }}\frac{{{\rm{g}}{\rm{.\beta }}{\rm{.\Delta t}}{\rm{.}}{{\rm{l}}^{\rm{2}}}}}{{{{\rm{\nu }}^{\rm{2}}}}}\]

\[{\rm{Gr = }}\frac{{{\rm{g}}{\rm{.\beta }}{\rm{.\Delta t}}{\rm{.}}{{\rm{l}}^{\rm{3}}}}}{{{{\rm{\mu }}^{\rm{2}}}}}\]

\[{\rm{Gr = }}\frac{{{\rm{g}}{\rm{.\beta }}{\rm{.\Delta t}}{\rm{.}}{{\rm{l}}^{\rm{3}}}}}{{{{\rm{\nu }}^{\rm{2}}}}}\]

\[{\rm{Gr = }}\frac{{{\rm{g}}{\rm{.\beta }}{\rm{.\Delta t}}{\rm{.}}{{\rm{l}}^{\rm{3}}}}}{{{{\rm{\lambda }}^{\rm{2}}}}}\]