Buckingham Palace office of the Monarchy. Not personally owned. Opens to the public to earn an income.
Clarence House his residence as POW, will likely vacate in due course. Not personally owned.
Sandringham inherited from his mother, personally owned. Holiday home.
Windsor Castle not personally owned. Does not live here. Open to the public to earn an income.
Highgrove personally owned. Lives here when not working. Opens to the public to earn an income.
Balmoral inherited from his mother, personally owned. Holiday home. Opens to the public to earn an income.
Birkhall is on the balmoral estate and as such is not "extra"
Castle of Mey belongs to a charitable trust. Charles does not own it. Opens to the public to earn an income.
his Romanian home he has an abroad house.
Llwynywermod in Wales as the POW it makes sense that he owned a home in Wales.
So he personally owns 5, though he inherited 2 of those on the death of his mother. No doubt in due course he will make changes to this.
3 belong to the Crown Estate (not personally owned by the Royal family)
1 is owned by a charity.
He Opens 4 of these properties to the public to earn an income for their keep / funds given to the govt.