 From the 2011 Census , the Office for National Statistics published that Plymouth 's unitary authority area population was 256 @,@ 384 ; 15 @,@ 664 more people than that of the last census from 2001 , which indicated that Plymouth had a population of 240 @,@ 720 . The Plymouth urban area had a population of 260 @,@ 203 in 2011 ( the urban sprawl which extends outside the authority 's boundaries ) . The city 's average household size was 2 @.@ 3 persons . At the time of the 2011 UK census , the ethnic composition of Plymouth 's population was 96 @.@ 2 % White ( of 92 @.@ 9 % was White British ) , with the largest minority ethnic group being Chinese at 0 @.@ 5 % . The white Irish ethnic group saw the largest decline in its share of the population since the 2001 Census ( <unk> % ) , while the Other Asian and Black African had the largest increases ( 360 % and 351 % respectively ) . This excludes the two new ethnic groups added to the 2011 census of Gypsy or Irish Traveller and Arab . The population rose rapidly during the second half of the 19th century , but declined by over 1 @.@ 6 % from 1931 to 1951 . 
