The 1951 census recorded Karai as comprising 1 hamlet, with a total population of 426 people (217 male and 209 female), in 71 households and 71 physical houses.[4] The area of the village was given as 364 acres.[4] 6 residents were literate, all male.[4] The village was listed as belonging to the pargana of Aldemau and the thana of Dostpur.[4]
The 1961 census recorded Karai as comprising 2 hamlets, with a total population of 451 people (218 male and 243 female), in 79 households and 75 physical houses.[5] The area of the village was given as 364 acres.[5]
The 1981 census recorded Karai as having a population of 766 people, in 110 households, and having an area of 147.31 hectares.[6] The main staple foods were listed as wheat and rice.[6]
The 1991 census recorded Karai as having a total population of 953 people (479 male and 474 female), in 127 households and 110 physical houses.[3] The area of the village was listed as 143.11 hectares.[3] Members of the 0-6 age group numbered 217, or 23% of the total; this group was 55% male (120) and 45% female (97).[3] Members of scheduled castes numbered 301, or 31.5% of the village's total population, while no members of scheduled tribes were recorded.[3] The literacy rate of the village was 34% (193 men and 57 women, counting only people age 7 and up).[3] 200 people were classified as main workers (199 men and 1 woman), while 0 people were classified as marginal workers; the remaining 753 residents were non-workers.[3] The breakdown of main workers by employment category was as follows: 161 cultivators (i.e. people who owned or leased their own land); 20 agricultural labourers (i.e. people who worked someone else's land in return for payment); 0 workers in livestock, forestry, fishing, hunting, plantations, orchards, etc.; 0 in mining and quarrying; 0 household industry workers; 0 workers employed in other manufacturing, processing, service, and repair roles; 0 construction workers; 1 employed in trade and commerce; 17 employed in transport, storage, and communications; and 1 in other services.[3]