A method and apparatus for assigning decoupling capacitors on an integrated circuit such that leakage power is minimized is provided. Particularly, the method and apparatus use an available capacitance area of an integrated circuit, a capacitance requirement of the integrated circuit, an available thin-oxide capacitance amount, and an available thick-oxide capacitance amount to generate an assignment that indicates what percentage of the available capacitance area should be filled with thin-oxide capacitors and what percentage of the available capacitance area should be filled with thick-oxide capacitors in order to meet the capacitance requirement and minimize leakage power attributable to the thin-oxide and thick-oxide capacitors.