Benhar had a population of 90 at the 2018 New Zealand census, a decrease of 9 people (−9.1%) since the 2013 census, and a decrease of 6 people (−6.2%) since the 2006 census. There were 39 households. There were 51 males and 39 females, giving a sex ratio of 1.31 males per female. The median age was 37.6 years (compared with 37.4 years nationally), with 18 people (20.0%) aged under 15 years, 18 (20.0%) aged 15 to 29, 48 (53.3%) aged 30 to 64, and 9 (10.0%) aged 65 or older.
