| Official Name: | Kostanjica |
| Other Name: | Castagna |
| Settlement Type: | Village |
| Pushpin Map: | Croatia |
| Pushpin Label Position: | bottom |
| Coordinates: | 45.365°N 13.7307°W |
| Subdivision Type: | Country |
| Subdivision Type1: | County |
| Subdivision Type2: | Municipality |
| Subdivision Name2: | Grožnjan |
| Unit Pref: | Imperial |
| Area Footnotes: | [1] |
| Area Total Km2: | 3.9 |
| Population As Of: | 2021 |
| Population Total: | 61 |
| Population Density Km2: | auto |
| Timezone: | CET |
| Timezone Dst: | CEST |
| Utc Offset: | +1 |
| Utc Offset Dst: | +2 |
| Postal Code Type: | Postal code |
| Postal Code: | 52429 Grožnjan |
| Area Code: | 052 |
Kostanjica is a village in the municipality of Grožnjan in Istria, Croatia.
According to the 2021 census, its population was 61.