Sumner is split between residential and industry, with a large industrial estate Sumner Park.
In the 2011 census the population of Sumner was 539, 48.4% female and 51.6% male.
The median age of the Sumner population was 29 years, 8 years below the Australian median.
61.6% of people living in Sumner were born in Australia, compared to the national average of 69.8%; the next most common countries of birth were New Zealand 5.4%, England 4.4%, Sri Lanka 3.5%, India 2.8%, South Africa 2%.
75.4% of people spoke only English at home; the next most popular languages were 2.6% Vietnamese, 2% Sinhalese, 1.8% Punjabi, 1.8% Arabic, 1.1% Maori (Cook Island).