The cheapest flight to Berlin you can get by boooking 12 days before departure.
The most popular airlines on the route Cologne - Berlin: Ryanair (FR), Germanwings (4U), Air Berlin (AB).
The cheapest flights you can book on the route Cologne - Bonn Airport (CGN) - Schonefeld (SXF).
Direct flights last about 1h 5min.
Direct flights available 7 days a week.
Direct flights: Ryanair (FR), Germanwings (4U), Air Berlin (AB).