Horowhenua District had a population of 33,261 at the 2018 New Zealand census, an increase of 3,165 people (10.5%) since the 2013 census, and an increase of 3,393 people (11.4%) since the 2006 census. There were 13,230 households. There were 16,143 males and 17,118 females, giving a sex ratio of 0.94 males per female. Of the total population, 6,087 people (18.3%) were aged up to 15 years, 5,244 (15.8%) were 15 to 29, 13,707 (41.2%) were 30 to 64, and 8,223 (24.7%) were 65 or older. Figures may not add up to the total due to rounding.