CDG to Chartres via public transpo

Instead of worrying about Metro vs RER, etc, here is a super easy way to do this trip: Take Le Bus Direct to Gare Montparnasse from CDG. http://www.lebusdirect.com/lignes-horaires/ligne-cdg-aeroport-paris-gare-montparnasse.html The first stop after you leave the airport is Gare de Lyon and the second stop is Gare Montparnasse. It's slower than the RER but on a Sunday morning, it should be okay. Allow four hours between the scheduled arrival for your flights and the train that you plan to take. Cost of the bus is € 17. You can buy your ticket online and have that set before you get to Paris. Tickets to Chartres from Paris are € 16 and trains leave just about once an hour. No need to be nervous. At CDG, (assuming that you are arriving at Terminal 1 or 2) follow the terminal signs that say "Bus" to the stop. At Gare Montparnasse, the bus arrives at Rue du Commandant Rene Mouchette right across from Pullman Gare Montparnasse and right in front of an entrance to Gare Montparnasse. It is a shorter walk to the trains from there than it would be from the Montparnasse-Bienvenue metro stop.

JHK has it exactly right. You might save a few euros using RER and Metro instead of Le Bus Direct, but it will be more complicated and tiring with your luggage. The bus will take you right to Gare Montparnasse (the second stop), your bags will be underneath, and you'll see the city from your window. Then an easy train ride, about an hour, to Chartres.

We looked into visiting Chartres upon arrival at deGaulle and concluded it could not be done before noon via public transportation.

In addition to getting your bags and clearing immigration, you still have to get to Montparnasse station. To physically be in Chartres before noon you have to board a train at 10:09 (weekday).

I'm not sure you will be able to print a TER ticket in advance, so even if you pay for the ticket before you leave the States you will still have to wait on a line to get the ticket printed. Montparnasse is a big place too, so be sure to allocate enough time. I'd want 45 minutes at least.

Also, will your parents have a car or a room in Chartres? Because if not there is the problem of your bags.

All of this is not absolutely impossible if you pack light and do not check your bag, if your flight arrives by 7 or so, and if there are not unexpected delays. Are you that nimble? If this will be your fist such trip I would not recommend it.

I hate to say this, but your parents should just drive up and pick you up if they have a car rented. It's not that far, and on Sunday the traffic should flow, while for you it's a hassle. We know a lot of people living further than Chartres who go up to pick up arriving friends and family.

Thanks all for help. My parents do have a rental car and a room when I get to Chartres, but they were just thinking with tolls and traffic it would be a hassle. I should say, I am confident and I'm not too nervous because I've traveled abroad before... More so, just trying to figure out if with my ONE checked bag (it's a duffel backpack and it's not super heavy) and myself, I can make it thru customs quick, get the bus ticket to the train and be there around mid afternoon. It's fine if it takes 3-4 hours; I just don't think my parents are wanting to leave Chartres and I think with y'alls help I can make it. My flight gets in at 9:45am and I will have euros with me but will not be able to catch the early morning train from Gare station. Thank you guys again! I know it will workout.

@ OP, I am sure that you will be fine. My now 18 year old daughter did this trip at age 16 alone and she has the worst sense of direction in the world. It was all written down for her and she used the parisbytrain's Gare Montparnasse information page to get a sense of what she needed to do. She says that she really committed the directions for what to do at Montparnasse to memory while on the bus. We were not in France at the time and I just asked her this morning if, with the benefit of hindsight, she would have needed for us to drive up to CDG to get her if we could have and she looked at me like I was crazy and said no. She said that she was nervous but not afraid; mainly she kept on thinking that she had missed signs and then just when she would think that she had made an error, she would see the next sign. Here is the Gare Montparnasse information page if you need it: http://parisbytrain.com/gare-montparnasse-photo-tour/. The page has one error that I caught. It says that the station is in the 6th arrondissement but it is actually in the 14th and 15th.

By mid afternoon should be a piece of cake. Early afternoon, even.