We do not have enough data on this route to provide a reliable graph showing how many days before departure it is the best to book.
However, usually the closer it is to the departure, the more expensive the tickets are.
The most popular airlines on the route Letterkenny - Dublin: Aer Lingus (EI).
The cheapest flights you can book on the route Donegal Airport (CFN) - Dublin Airport (DUB).
Direct flights last about 0h 55min.
Direct flights available on: Saturday.
Direct flights: Aer Lingus (EI).