The present invention provides a method for estimating the average-case activity in a digital circuit. The method includes the steps of assigning initial activity values to outputs of flops in the digital circuit, and repeatedly updating the activity values in an iterative procedure until a predetermined termination criterion is met. The updating of the activity values uses a combination of standard probability updating techniques and predetermined formulae for obtaining the activity values of predesignated types of circuit elements in the digital circuit. The predesignated types of circuit elements include, for example, one or more of a clock-gated flop, an enable flop and a flop with a recirculation multiplexer.