CDG to Rouen

Easy peasy! Take the RER B from CDG to Gare de Nord, transfer to the RER E at Magenta. Take it one stop to Haussmann St Lazare. The station is just a short walk or cab ride. You catch the train at Gare St Lazare to Rouen. For best price, buy your tickets 2-3 months ahead as prices increase closer to departure date. There's a great app for dealing with the Metro in the App Store.

Thank you so much!

There's really no need to buy your tickets very far in advance. I went a couple of weeks ago and we got cheap tickets 3 days in advance. But, if your dates are set there's no harm in purchasing early.

I have a question, we are also planning on taking the train to Rouen from Paris. Since there could be flight delays we will want to wait to buy tickets. I know they will be more expensive but will there be a problem if we purchase our tickets when we arrive at the train station? Or should we risk missing our train by buying a ticket earlier?

we have had lots of late planes so if we are doing an ongoing train trip (have done this often in Rome) then we buy when we get there and just pay more. The savings are fairly substantial buying early but you have to be prepared to lose the ticket. One approach is to give yourself reasonable time e.g. 4 hours and then just resign yourself to buying new tickets if necessary.

One issue with US credit cards is you may have to stand in a long line to buy tickets -- it was over an hour the day we wanted to go to Giverny and we missed our desired train.

our experience has been similar to @janettravels44 with flights arriving late. Which is a quandry frequently brought up on the forums. Cheap tickets are the ones purchased in advance, but nobody likes waiting for a few hours when they book a train that takes a reasonable flight delay into account.

My solution is to break the trip down into 2 parts. Flights may be delayed but they usually arrive eventually on the scheduled day. So the arrival day (or afternoon or nite) we stay in the city we flew into. Depending on when we arrive there's time for a walk, maybe a museum or sight, and dinner. And after a flight from the US its nice to have a nite's rest before pushing on. The next day we leave in the morning on that cheap advance-purchase train ticket, no worries about missing the train or having hours to wait.

Philip - just to clarify - When we switch to RER E at Magenta and take it to Haussmann St. Lazare, we will not arrive IN Gare St. Lazare? We will still need to walk from Haussmann to the station? We don't mind walking too far, but will have luggage. Would it be a 5-10 min walk or longer than that? Thanks in advance!

Yes. There is a 8 to 10 minute walk to the station. Enjoy a coffee and croissant along your way!

Now that is a GREAT idea! Thanks!