Originally Posted by Flying Lawyer

However: Easiest journey: Take the TXL Bus in front of the main terminal building. The bus stop will be between 30 and 150 meters from your gate, is clearly signposted and can't be missed. Don't bother buying a ticket from the machines, but buy it from the driver. Ask for Ticket "ABC". This is good for the entire journey. Get of the bus at the Central Railway Station (called Hauptbahnhof) and go to track 12. From there take Regional Train Number 7 (-45 past the hour) or 14 (-10 past the hour) calling at Schönefeld Airport (5th stop). Total travel time is about an hour. If you miss one train, worst case 1.30.