German Grammar Explained /

Genitive with names

As we have already seen, when forming the genitive with proper names, it's pretty straight forward. All you have to do is add an -s:
Wo sind Annas Bücher?
Where are Anna's books?
Das ist Andis Auto.
This is Andi's car.
So it's a bit like English, just without the apostrophe. That's easy.
Exactly! However, there are some cases where the apostrophe has to be used.
I knew there was a catch...
Names that end in -s, -ss, -ß, -tz, -z, -x are treated differently. Instead of adding an s, we use the apostrophe to drop it.
Ich war mit Fritz' Familie im Urlaub.
I was on holiday with Fritz' family.
Ines' Kleid ist blau.
Ines' dress is blue.
Hast du Felix' Rucksack gesehen?
Have you seen Felix' rucksack?
Okay, that really is like English.