Don’t trust the airport website (outdated), nor the tourist information (not sure), neither the travel agencies (trying to sell their private bus ticket).
So here is a little recap of your options to go to the international airport of Bangkok (Suvarnabhumi Airport) from Kao San Road:
Take a taxi : about 400 Baths
Take a private bus or a minivan : 150 Baths per person
Go by public transport ( bus+train ) : 50 Baths per person
Of course the last option is way better, because the time of travel is relatively well fixed and doesn’t depend on traffic jams. also it is faster (a lot).
First you have to walk to the democracy monument (10 minutes from Kao San Road, walking slowly), then to take one of the many public buses which goes from “democracy monument” to “airport link” (the 556 for example, max 20 minutes).
From the airport link go inside the super-modern train to International Airport (normal service : 35 Baths, 20 minutes, express 90 Baths).
You get off inside the airport, take the elevators and check-in!
Merci pour ces renseignements pratico-pratiques. Et depuis Invalides, on fait comment, Rémi ? 😉
Prendre le bus 82 jusqu a Auguste Comte, puis le RER B jusqu’a Aeroport Charle de Gaulle, prendre ensuite l’avion pour Bangkok, on arrive directement dans l’aeorport, comme c’est pratique!