A method of estimating a leakage for a plurality of transistors in an integrated circuit that accounts for narrow channel effects includes determining an expected total leaking transistor width for the collection; determining an expected total number of leaking transistors for the collection; determining an average width of a leaking transistor from the expected total leaking transistor width and expected total number of leaking transistors; estimating a leakage for a transistor of the average width; and determining the estimated leakage for the collection of transistors by multiplying the leakage for a transistor of the average width by the expected total number of leaking transistors for the collection.