This paper presents a new derivation of the free energy of micellar solutions. From this free energy a micelle size distribution can be calculated. By using a density functional model for the bulk contribution to the free energy, and a simple approximation for the micelle (proper) contribution, we develop a simple, tractable model for the free energy of micellar solutions. We also explore the relationship of our model to the standard thermodynamic models used to study micellar solutions. We present model calculations using combinatorial minimization of the free energy, paying particular attention to entropic effects on the micelle size distribution. (C) 2003 American Institute of Physics.