Postal codes in Croatia are 5 digit numeric.
Zagreb City and Zagreb County have one, each other first level administrative country subdivision, i.e. one of the counties of Croatia, has its own range.
Three cities have a postal code with 4 zeros: 10000 Zagreb, 20000 Dubrovnik, 40000 Čakovec.
After independence, Croatia went on to use the 5 digit numeric postal codes once assigned to the Socialist Republic of Croatia (within SFR Yugoslavia).
The system had assigned the ranges 4xxxx and 5xxxx to the republic.