In the 2016 census, Plainby had a population of 44 people.[9]
In the 2021 census, Plainby had a population of 56 people.[1]
Education
There are no schools in Plainby. The nearest government primary schools are Crow's Nest State School in neighbouring Crows Nest to the east, Haden State School in Haden to the north-west, and Goombungee State School in Goombungee to the south-west. The nearest government secondary schools are Crow's Nest State School (to Year 10) and Highfields State Secondary College in Highfields to the south.[10]