Khao San Road is a short street in central Bangkok. It is a popular place to stay for tourists especially backpackers. The street is more crowded at night because both locals and tourists go to the pubs and restaurants there.
The weak point of staying at Khao San Road is this road does not connect with any express train. So, it sometimes is difficult to reach the other parts of the city. In this post, I will share you how to get from Khao San Road to BTS Skytrain, the effective transportation mode that covers the major parts of Bangkok and connects with MRT Subway and Chao Phraya Express Boat.
The closest BTS Skytrain stations to Khao San Road are Siam Station, Ratchatewi Station, and National Stadium Station. The distance between Khao San Road and these three stations are about 5 kilometers.
The easiest way is to take taxi which should cost around 60 baht and take around 20 minutes to half an hour (it could take more money and time if the traffic jams are bad).
Another option is to take public bus. The bus number 15 and 47 go to Siam Station and National Stadium Station. The bus number 2 and 511 go to Ratchatewi Station. But, I do not recommend you to take bus if you are not familiar with Bangkok area.
And the last option is to take the boat at Saen Saeb Canal, but you have to walk around 1.5 kilometer or 20 minutes from Khao San Road to Panfa Leelard Pier to take the boat and get off at Saphan Hua Chang which is close to National Stadium BTS Station and Ratchatewi Station.
Well, my recommendation option for tourist is to get from Khao San Road to BTS Skytrain at Saphan Taksin Station. It is not the shortest path, but it is more comfortable. Besides, it is less chance to get lost and you do not have to face the traffic jams. With this option, you just have to walk to Phra Arthit Pier (around 800 meters, 10-minute walk). Then, take the Chao Phraya express boat to Sathorn Pier, which is only a minute walk to Saphan Taksin BTS Station.
Hope this information helps