Getting out of Charles de Gaulle

The rule of thumb is 4 hours. If your flight is on time you probably will make it; I'd take a cab. The unknowable part is how long immigration takes. In the last 3 arrivals for us, it took us 90 minutes, 45 and 15 -- alas when it was 15, they trapped about 20 bags including ours in some kind of equipment snafu underground and kept telling us our bags were on the belt so if they were not there someone had stolen them and since we were right there we knew that was not true. Finally someone investigated and they found about 20 bags mooshed up in some sort of underground traffic jam and they were delivered to the carrier -- so it was close to 90 minutes to the cab.

It will be an hour or more to Montparnasse; cabs can use the bus lanes and they can deliver you right to the station. Be sure you know which platform -- the main ones or Vaugirard satellite station. It will say on your ticket. We have never waited long for a cab at CDG (NEVER go with anyone who offers or directs you to a different line -- go to the official queue which is well signed and take the cab the dispatcher directs you to. It is 65 to Montparnasse.

I'd probably risk it BUT the cost is buying another train ticket when you get to the station if you get held up or have a late plane. Most US flights are a litlte early but our plane last fall came in two hours late. Decide which risk you are happier with -- getting to your destination later or buying another train ticket.

One can never be certain of anything...flight delays, long passport line. But in April we arrived at CDG at 1pm on a Saturday, got in the very short official taxi line (don't let anyone distract you with an another offer while walking to the line.) We took our taxi to our hotel in the 6th arrondissement not all too far from Montparnasse and we were checking in by 3pm. (I felt like there was some advantage to arriving on the weekend vs weekday with regard to traffic, but I don't know that for sure. I just know traffic wasn't bad.)

We took the train out of Montparnasse days later. The station is big, but there were helpful employees who spoke English, willing to direct us to the correct platform; and of course there are reader boards too, but we wanted to double check that we understood where we were going.

Too close for my comfort. Is there a later train?

Montparnasse station is huge, I would study a map of the station before arriving to know where to go, what to look for...

You should be fine if your plane is on time, or even a little late. If not, you can always buy a ticket for a later train. But you’ve given yourself four hours basically, which if your plane is on time, will be fine.

I think you are fine. My rule of thumb (tested over probably a dozen recent trips to Paris) is that it takes two hours from touch down to walking into my hotel lobby (Porte Maillot stop on the 1 line) via RER/Metro.

Thank you all for your advice!

Useful website for CdG:

https://easycdg.com/

We ran into a situation where we missed our TGV ( by several days eventually). I used the SNCF app and was able to change pretty easily. I just had to pay for the fare difference.

So much depends on your flight arriving on time. There's really no predicting that. Having a flexible ticket is always a good idea for your situation.

I regularly fly through Iceland, so I'm arriving with a stamped passport and carry-on bag only. My times don't include waiting for immigration or bags.

It takes me right at an hour to get out of the airport on an RER heading downtown (walk from plane to station, buy ticket, wait for next train) plus about another hour to get downtown.

A taxi will save time spent buying a ticket and waiting for the next train but might also get you into traffic. If worse comes to worse, you might catch a taxi to north Paris and catch a metro/RER from there to Montparnasse.