The carrier had a standard displacement of 15,740 tons, and a deep displacement of 19,550 tons. Her length was between perpendiculars and at her longest point, with a beam of and a draught of . "Sydney" was fitted with four Admiralty 3-drum boilers, which provided steam to Parsons single reduction geared turbines; these supplied to the two propeller shafts, and allowed the ship to reach . The average size of the ship's company in peacetime was 1,100, but could be increased to 1,300 for wartime deployments. Refitting the ship to serve as a transport reduced the standard displacement to 14,380 tons and the ship's company to a core of 544, which was supplemented by trainees and personnel from the Royal Australian Navy Reserve when required.