Here's a listing of the twenty largest countries in the world by area, in both square kilometers and square miles. 1  Russia: 17,075,200 km 2 (6,591,027 mi 2).2  Canada: 9,984,670 km 2 (3,854,082 mi 2). 3  United States: 9,631,418 km 2 (3,717,727 mi 2).4  China: 9,596,960 km 2 (3,704,426 mi 2).ere's a listing of the twenty largest countries in the world by area, in both square kilometers and square miles. 1  Russia: 17,075,200 km 2 (6,591,027 mi 2). 2  Canada: 9,984,670 km 2 (3,854,082 mi 2). 3  United States: 9,631,418 km 2 (3,717,727 mi 2). 4  China: 9,596,960 km 2 (3,704,426 mi 2).