fˈɛɹfiːld hæd ɐ pˌɑːpjʊlˈeɪʃən ʌv fˈoːɹ,θɹˈiːhˈʌndɹɪd ˈeɪɾi θɹˈiː æt ðə tˈuː θˈaʊzənd ˈeɪtiːn nˈuː zˈiːlənd sˈɛnsəs, ɐn ˈɪŋkɹiːs ʌv θɹˈiːhˈʌndɹɪd nˈaɪnti pˈiːpəl nˈaɪn.ˈeɪt pɚsˈɛnt sˈɪns ðə tˈuː θˈaʊzənd θˈɜːtiːn sˈɛnsəs, ænd ɐn ˈɪŋkɹiːs ʌv fˈoːɹhˈʌndɹɪd θˈɜːɾi fˈaɪv pˈiːpəl ɪlˈɛvən.zˈiəɹoʊ pɚsˈɛnt sˈɪns ðə tˈuː θˈaʊzənd sˈɪks sˈɛnsəs.
Fairfield had a population of 4,383 at the 2018 New Zealand census, an increase of 390 people (9.8%) since the 2013 census, and an increase of 435 people (11.0%) since the 2006 census.