Radius as a function of core and envelope mass for planets at 100 Myr and 0.1 AU. The left panel shows the radius as found from the full expression (Eqs. (23) and (25)) while the right one uses the simple approximation of Eq. (26). The dotted, solid, and dashed lines show the radius for envelope masses of a 1 M_⊕ core of M_e,1 = 0.01, 0.03, and 0.1M_⊕. Black, blue, and red lines show p_e = 0, 1, and 2, the power law exponent representing how H/He envelope mass M_e scales with core mass, .