| New calendar | Friday, 21 May 2027 |
|---|---|
| Old calendar | Thursday, 3 June 2027 |
| Bulgarian | Friday, 21 May 2027 |
| Romanian | Friday, 21 May 2027 |
| Albanian | Friday, 21 May 2027 |
Spellings and nicknames
Constantin, Constantine, Costache, Costas, Costel, Costica, Costică, Costin, Costinel, Dean, Dinos, Gus, Konstadinos, Konstandin, Konstantino, Konstantinos, Kosta, Kostandin, Kostaq, Kostas, Kosti, Kote, Kotsos, Koçi, Takis, Κωνσταντίνος, Κωστάκης, Κώστας, Ντίνος, Котето, Коце, Кочо