There are really some exceptions to the set of rules for building the plural in Croatian ...
So, we would like to recommend:
Try to learn the plural form together with the singular – each time you encounter a new noun you want to add to your vocabulary.

1. Please look out for masculine Croatian nouns ending in g, h or k:
   These consonants at the end of the word will change when adding an -i for building the plural.
   Please commit the following rules to memory:
   g → zi
   💡 For example:
   suprug – supruzi (husband – husbands)
   h → si
   💡 For example:
   tepih – tepisi (carpet – carpets)
   k → ci
   💡 For example:
   jezik – jezici (language – languages)
2. Some (not all!) monosyllabic masculine nouns form their plural with -ovi.
   💡 For example:
   grad – gradovi (city – cities)
3. Some (not all!) polysyllabic masculine nouns build their plural with -ovi.
   💡 For example:
   cvijet – cvjetovi (blossom – blossoms)
4. Monosyllabic masculine nouns ending in a soft consonant, form their plural with -evi.
   💡 For example:
   čaj – čajevi (tea – teas)
5. Some (not all!) polysyllabic masculine nouns build their plural with -evi.
   💡 For example:
   tečaj – tečajevi (course – courses)
6. Some masculine word stems drop an “a” when put into their plural.
   💡 For example:
   tjedan – tjedni (week – weeks)

In the next chapter you will get to know the exceptions for the plural of feminine nouns.