1 Males average 3.4 to 4.6 m (11.2-15.1 ft.) and weigh about 1,500 kg (3,307 lb.). 2  Females average 3 to 4 m (9.8 to 13.1 ft.) and weigh about 1,360 kg (2,998 lb.).  Beluga whales reach full size at about 10 years.