Kainga is a settlement on the southern bank of the Waimakariri River, just north of Christchurch, in Canterbury, New Zealand. It lies immediately to the south of Kaiapoi, on a small road leading northeast from State Highway 1.

Originally established as a small group of fishing huts on the south side of the Waimakariri, it later developed into a small residential area. A small forestry plantation lies to the southeast of the settlement.

Kainga is in an SA1 statistical area which covers 2.37 km (0.92 sq mi). The SA1 area is part of the larger Styx statistical area.

Historical population

Year	Pop.	±% p.a.
2006	195	—
2013	201	+0.43%
2018	195	−0.60%
Source:

The SA1 statistical area had a population of 195 at the 2018 New Zealand census, a decrease of 6 people (−3.0%) since the 2013 census, and unchanged since the 2006 census. There were 81 households, comprising 105 males and 93 females, giving a sex ratio of 1.13 males per female. The median age was 39.6 years (compared with 37.4 years nationally), with 36 people (18.5%) aged under 15 years, 33 (16.9%) aged 15 to 29, 105 (53.8%) aged 30 to 64, and 21 (10.8%) aged 65 or older.

Ethnicities were 93.8% European/Pākehā, 16.9% Māori, 3.1% Pasifika, 1.5% Asian, and 1.5% other ethnicities. People may identify with more than one ethnicity.

Although some people chose not to answer the census's question about religious affiliation, 75.4% had no religion, 16.9% were Christian, 1.5% had Māori religious beliefs and 1.5% had other religions.

Of those at least 15 years old, 15 (9.4%) people had a bachelor's or higher degree, and 48 (30.2%) people had no formal qualifications. The median income was $31,200, compared with $31,800 nationally. 15 people (9.4%) earned over $70,000 compared to 17.2% nationally. The employment status of those at least 15 was that 84 (52.8%) people were employed full-time, 24 (15.1%) were part-time, and 6 (3.8%) were unemployed.