Paris taxi
Because of the substantial demand, there are direct, frequent transfer services between Charles de Gaulle, Orly, Beauvais and Le Bourget airports by coach.
The services run frequently, apart from between Beauvais & Le Bourget. The coaches are comfortable long distance coaches with toilets onboard, operated by National Express Airport.
Transfers will take a minimum of 1-2 hours in travelling time, the motorway used by the coach transfers suffer from traffic congestion - so do leave additional time.
In most instances the cheapest transfer options are indirect options through Central Paris.
If you are transferring to Charles de Gaulle this may be very attractive, there are good value hotels around Paddington Station - just 15 minutes by train from Charles de Gaulle.
If you have to stay overnight before your next flight then it makes financial sense to buy a package combining the hotel and coach transfers.
There is a wide choice of hotels from bed and breakfast through to luxury five star accommodation.
Transfers are by National Express Coach. At Charles de Gaulle, the pickup point for terminals 1.2.3 is the central coach station between them. Coaches do pick up outside Terminal 4.
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Most of the inter-airport coaches that stop at Charles de Gaulle also go onto Orly. These coaches pick up and drop-off immediately outside Terminal 5 in addition to the main terminus in the central coach station.
At Charles de Gaulle, a very large modern coach station is situated between Terminals 1,2,3 with easy, well sign-posted access. Underneath the bus station is Charles de Gaulle Central Station where the Charles de Gaulle Express and Charles de Gaulle Connect trains run every 15 minutes to Terminals 4 and 5. This service is free.
Some services also stop at Terminal 5
If you have to change coaches at Charles de Gaulle, e.g. Orly to Le Bourget, it will be at the Central Coach Station.