Entrainment of rotating convection is investigated using a large-eddy simulation (LES) model. The model is forced with a uniform destablizing surface buoyancy flux, which varies by about an order of magnitude. The initial mixed layer depth varies from 0 to 3000 m and the background stratification varies over two orders of magnitude. The vertical component of the Earth's rotation rate at 30, 45, and 60¿N are used. The corresponding flux Rossby number varies about three orders of magnitude. An empirical formula for the ratio of entrainment buoyancy flux to the surface buoyancy flux as a function of the Rossby number is derived. A bulk mixed-layer model for rotating convection is formulated based on the entrainment formula. It is suggested this formula can also be used to tune other 1-D models used in ocean general circulation models to account for the effect of Earth's rotation on convection.