How to go from Orly Airport to CDG Paris ?

To commute between Orly airport and CDG airport in paris you have 2 main options ;

Trains ( RER line B ) , Taxis .

RER line B (suburban Train):
There is « RER B » that goes from the center of Paris to « Antony » train Station, there you have to take another special automated train named « Orlyval » to airport. The ticket cost 12-13 €. travel time is at least 35min. Train  intervals are 3-4 per hour. 

Since RER line B almost connect two airports ;

So you can come the same way back to Paris and continue To the CDG airport, once you arrive in either « Chatelet » or « Gare de Nord » train station, make sure you be in right train for CDG! Not all RER B trains go to CDG. Travel time is about 75 min.

If you have a family or many luggages with you trains and buses for Orly are not a good choice for you, it will be difficult to carry all that through stairs and crowded trains, buses and changes etc.. 

Taxi; 
Is the easiest and surest way to commute between Orly and CDG,travel time is about 50 min (in normal traffic) and cost about 60€. 
During the night or early morning taking a Taxi is recommended, rather than trains ! 

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