See the full article at Roissy-Charles de Gaulle Airport to Paris by Train
Line => RER B (Blue)
Direction => Aéroport Charles de Gaulle / Mitry – Claye
Arrival Station => Aéroport CDG 1, Aéroport CDG 2 (Zone 5, €8,20)
To get to Airport Roissy-Charles de Gaulle (CDG) from Paris, use the suburban train line RER B (Blue) at a cost of €8,20, one way, requiring roughly 40 minutes.
Within Paris the RER B line travels from south to north, stopping at Denfert-Rocherau, up past the Luxembourg Gardens (station name: Luxembourg), St. Michel/Nôtre Dame, Châtelet Les Halles, Gare du Nord, then continues north east, making up to 9 more stops on its way to CDG terminals 1 and 2.
Note that not all RER B line trains stop at Charles de Gaulle airport. The easiest way to determine whether the next RER B train arriving at a station goes to CDG is to look at the RER overhead station stop panels on the train platform. If a light is lit next to Aeroport CDG 1 or Aeroport CDG 2 TGV, the next train will stop at the airport. You’ll also be able to tell how many stops the next train will make between Paris and the Airport by counting the number of stations in between Gare du Nord (the last Parisian station) and the airport stations, Terminals 1 and 2. Obviously, the train making zero stops in between Gare du Nord and the airport will be a bit quicker, usually by about 12 minutes.
Another way to tell if the next train is going to the airport is… Read the rest of the article at Paris by Train…