The preposition "ab"
The German preposition "ab" means "from ... onwards" and tends to be used without a following article or determiner. It normally takes the dative case, but it can also take the accusative case in time phrases when it is not followed by a determiner.
The German flag Grammar 16: The preposition "ab"
Das ist ab sieben Uhr im Restaurant
("That is from seven o'clock onwards in the restaurant")
Kinderermäßigung ab 12 Jahre(n)
("Child reductions for 12-year-olds and above.")
Eine Reservierung ist ab 4 Nächte(n) möglich.
("A reservation is possible for stays of longer than four nights.")
Ab Hauptbahnhof direkt per U-Bahn
("From the central station you can travel directly using the underground")
The prepositions "per" and "pro"
Take care not to confuse these two prepositions. The German preposition "pro" should be used to translate English "per". The German preposition "per" on the other hand is used mainly in commercial German to translate "by" as in a means of doing something, often a means of transport.
Both "per" and "pro" take the accusative case, but are almost always used without a following determiner.
The German flag Grammar 17: The prepositions "per" and "pro"
Pro
Was ist der Preis pro Tag?
("What is the price per day?")
Ein Einzelzimmer kostet 85 Euro pro Tag.
("A single room costs 85 euros per day.")
Die Tagungspauschale ist 25 Euro pro Person.
("The conference charge is 25 euros per person.")
Die Äpfel kosten 50 Cent pro Stück.
("The apples cost 50 cents each.")
Per
Wie Sie uns per Bahn finden:
("How you can find us by rail:")
So erreichen Sie unser Hotel per Straßenbahn:
("This is how you can reach our hotel by tram:")
per Post
("by post")