"Perseus" had an overall length of , a beam of , and a draught of at deep load. She displaced at standard load. Each of the ship's two sets of Parsons geared steam turbines drove one propeller shaft. Steam was supplied by four Admiralty three-drum water-tube boilers operating at a pressure of . The turbines were designed for a total of and gave "Perseus" a speed of . The ship carried of fuel oil which gave her a range of at .