| Official Name: | Kalai |
| Native Name: | কালাই |
| Settlement Type: | Upazila |
| Subdivision Type: | Country |
| Subdivision Name: |  Bangladesh |
| Subdivision Type1: | Division |
| Subdivision Name1: | Rajshahi |
| Subdivision Type2: | District |
| Subdivision Name2: | Joypurhat |
| Population Total: | 143197 |
| Population As Of: | 2011 |
| Population Density Km2: | auto |
| Area Total Km2: | 166.29 |
| Timezone: | BST |
| Utc Offset: | +6 |
| Coordinates: | 25°N 89°W |
| Postal Code: | 5930 |
Kalai (Bengali: কালাই) is an upazila of Joypurhat District in the Division of Rajshahi, Bangladesh.
Kalai is located at 25.0583°N 89.1833°W. It has 38,745 households and total area 166.29 km2.
According to the 2011 Bangladesh census, Kalai Upazila had 38,745 households and a population of 143,197. 26,847 (18.75%) were under 10 years of age. Kalai had a literacy rate (age 7 and over) of 49.82%, compared to the national average of 51.8%, and a sex ratio of 1021 females per 1000 males. 16,464 (11.50%) lived in urban areas.[1] [2]
As of the 1991 Bangladesh census, Kalai has a population of 114183. Males constitute 50.86% of the population, and females 49.14%. This Upazila's eighteen up population is 60864. Kalai has an average literacy rate of 23.5% (7+ years), and the national average of 32.4% literate.[3]
Kalai Upazila is divided into Kalai Municipality and five union parishads: Ahammedabad, Matrai, Punot, Udaipur, and Zindarpur. The union parishads are subdivided into 109 mauzas and 148 villages.
Kalai Municipality is subdivided into 9 wards and 34 mahallas.[4]
The famous educational institutions of this Upazila are: