A method, a computer program, and an apparatus are provided for generating circuit energy models for a macro using clock gating inputs. Circuit energy models are used to estimate system power consumption. The present invention enables circuit energy models to be created for macros that contain clock gating inputs. Power tables are created based upon the macro's input switching factor percentage and the clock activation percentage. These power tables are generated from a minimum number of power simulations. By using clock activation percentage as a parameter accurate energy tables are produced.