I found out that data about this which can be found on various internet sites is often not reliable. For example "Virtual Prague" website claimed that the area of the Prague Castle is 45 ha. I checked it in Google Maps and in reality it is about 10 ha. The website of Malbork Castle exaggerated less, it claimed that the castle covers 20 ha, while according to Google Maps it is closer to 15 ha.

Malbork Castle in Poland:



Hradczany, Prague (Czechia):



Wawel, Cracow (Poland):



Another source claims the following for these castles:

Malbork - 143,591 m2
Hradczany - 66,761 m2
Wawel - 55,932 m2

Of course rankings in terms of cubature will be slightly different than in terms of area.

=================

Krzyżtopór and Ogrodzieniec Castles appear to be around 3 ha each in Google Maps:

https://www.google.com/maps/place/Za...7!4d19.5520942

https://www.google.com/maps/place/Za...3!4d21.3104662

According to another source, cubaure of Krzyżtopór is 70,000 m3, area of the castle is 1.3 ha and of the gardens around it 1.6 ha (so in total around 3 ha indeed, as Google Maps suggests). The total length of walls is 600 meters.

https://www.krzyztopor.org.pl/zamek1/index.php/historia

See also:

https://www.eupedia.com/forum/thread...al-Heritage-EU