Borei nafashot apple

Hi, do I say Beracha acharona on a regular sized apple? Is an apple considered a kezayit and enough to say a Beracha acharona?

Yes. A kezayit is the equivalent to 1/6th of a machine matza. A regular apple is several times that and would therefore necessitate a Bracha acharona

Thank you. So when it comes to bread, to have enough to Say Birkat Hamazon… would that be about 1/4 of a pita bread? 1/2 of a challah roll?

Sounds good