| Kalaiya, Nepal | |
| Native Name: | कलैया |
| Settlement Type: | Sub-Metropolitan City |
| Pushpin Map: | Nepal Madhesh Province#Nepal |
| Pushpin Label Position: | bottom |
| Pushpin Mapsize: | 300 |
| Pushpin Map Caption: | Location in Nepal |
| Coordinates: | 27.0333°N 85°W |
| Subdivision Type: | Country |
| Subdivision Name: | Nepal |
| Subdivision Type1: | Province |
| Subdivision Type2: | District |
| Subdivision Name1: | Madhesh |
| Subdivision Name2: | Bara |
| Leader Title: | Mayor |
| Leader Name: | Binod Prasad Shah (CPN-UML) |
| Leader Title1: | Deputy mayor |
| Leader Name1: | Rausan Parwin (CPN-UML) |
| Area Total Km2: | 108.94 |
| Population Total: | 141,179 |
| Population As Of: | 2021 |
| Population Footnotes: | [1] |
| Population Density Km2: | auto |
| Population Blank1 Title: | Ethnicities |
| Population Blank2 Title: | Religions |
| Postal Code Type: | Postal code |
| Postal Code: | 44400 |
| Area Code: | 053 |
| Timezone: | NST |
| Utc Offset: | +5:45 |
Kalaiya is a sub-metropolitan city and serves as the headquarters of Bara District in Madhesh Province, Nepal. At the time of the 2021 Nepal census, it had a population of 141,179 people residing in 28,645 individual households.
Kalaiya is considered to be the gateway to the Gadhimai temple.