There are three main options for getting to Chiang Mai, which include by air, road, or rail.

International Flights:

The majority of visitors to Thailand fly into the Bangkok International Airport , the countries largest and busiest airport.  If flying from certain international locations such as Luang Prabang, Singapore, Taipei, Kunming, Mandalay, or Chittakong, it is possible to fly directly into the Chiang Mai International Airport , but this is generally not an option.

Domestic Flights:

From Bangkok to Chiang Mai have become extremely cheap.  Round trip fares as low as $40 are not uncommon.  If you fly to Chiang Mai, you will find getting around the airport to be quite easy as it is relatively small.  You can download a PDF Map of the airport which details the entire ariport and specifically the arrivals area.  If someone is meeting you the map indicates the meeting area.

If you plan to take a metered taxi on into town, ask for small notes for your taxi when you exchange currency. The exchange booths are familiar with the request, will do so willingly and give you a good supply of small bills.  Many taxi drivers either do not have small change, or will tell you they don’t, possibly hoping you will let them keep a large note/bill to avoid a problem or delay, the cost to any Chiang Mai area hotel is THB120 – Further Taxi Information linked here.

Buses:

The least expensive method is to take a bus, but this is also the least comfortable.  Even though most tourist buses have air conditioning, reclineable seats, and play movies, people who take this ten hour trip do not consider it very comfortable.

Buses from Bangkok to Chiang Mai depart at least every hour between 05:30 and 22:00 from Mo Chit (Northern) Station. Mor Chit is the last BTS station on the line.

The bus takes roughly 10 hours. VIP buses are recommended (fare THB400 – 600), offered by either the government or private companies. These can also be arranged from travel agents.

Renting a car:

In Bangkok and driving to Chiang Mai is another option.  This provides the most freedom to explore side roads and non tourist areas.  Make sure to check out the Driving in Thailand Page before choosing to get behind the wheel. Affordable car rentals in Chiang Mai

Passenger Trains:

The trains in Thailand are quiet punctual and it is a safe and comfortable way to travel. The trains are Air-conditioned. Most journeys by train are overnight and take approximately 12 to 15 hours.

Night trains between Bangkok and the North is a good way to travel since it will save you a night in a hotel. The bad thing about it is that they are so popular that they are almost always full.

Trains for Chiang Mai are always very busy. Try to purchase your ticket 2 to 3 days in advance. If you decide to take a train, when you arrive in Bangkok, plan your Chiang Mai trip and purchase your train ticket right away.

Main Station phone numbers: They usually speak good English, but the phone lines are often busy

– Bangkok Hua Lampong main Railway Station: (02) 223-3762, 224-7788 or 225-0300, extension 5100-01

– Chiang Mai Railway Station: (053) 245-363 / 4 or 247-462

NOTE:

• The sleeper trains, 2nd class is very nice, with a clean berth. You have a choice between, Upper berth (smaller and cheaper), Lower berth (slightly larger, and with the window, also slightly more expensive.)

• A second choice is also offered: Fan compartment, noisy since window is open, but with thief-shutter protection.

• Air-conditioned, very cold, but silent. Advisable in the warm or raining season.

• Trains runs everyday, prices vary on each train and category that you take.

• Best to take the Sleeper trains.

• Avoid the Sprinter train. – Sprinter train is a Diesel car with no sleeping berth. One runs during the day and one during the night.

• Sleeper trains and Diesel trains, both have seat 2nd class air-condition.

The most convenient:

• Special Express Train 5, departs Bangkok 19:40/arrival Chiang Mai 07:55

• Rapid Train 35, departing Bangkok at 06:40/arrival Chiang Mai at 19:35

• Sprinter Diesel Rail Car 907, departs Bangkok at 08:10/arrival Chiang Mai 18:50.

• Fare for a 2nd class air-condition seat is THB471, Lunch box included.

 

Visit Chiang Mai by Train for information about this mode of transportation.

source: TripAdvisor