The cheapest way to the airport. Nothing listed is quicker.
FEX airport express
FEX · DB Regio, on a VBB ticketPickup, hours & luggage
Boards at. Berlin Hauptbahnhof, on the lower level — or Potsdamer Platz or Südkreuz, further down the line
An ordinary ABC single — the express carries no supplement. A 4-Fahrten-Karte is EUR 16.80 for four rides, one coupon per person per journey: four people travelling together share one card and pay EUR 16.80 instead of EUR 20.00.
Luggage. A regional train with racks; it is built for the route.
Hours. Every 15 minutes from about 03:07 to 23:52, plus two much earlier trains at 00:52 and 01:52 — nothing runs between 01:52 and 03:07.