Istanbul has two international airports that serve the city. One is located on the European side while the other is on the Asian side. Both are well-connected to the city center through shuttle buses.
Atatürk International Airport, located on the European side of the city in Yeşilköy, is the main airport in Istanbul and also the largest. It’s a hub for Turkish Airlines and can reach many destinations throughout the world on direct flights. There are two terminals, one for domestic and another for international flights. The very dated and crowded airport will be replaced with a brand new bigger airport near the Black Sea coast in the near future.
The other airport is Sabiha Gökçen International Airport, which is a hub for Pegasus Airlines. It’s located in Pendik on the Asian side of the city. I always enjoy flying out of this airport because it’s much newer and usually not as crowded and hectic as Atatürk Airport, although it already exceeds its capacity of 25 million passengers per year. The drawback is the distance from the city center and the time it takes to get there. It serves several domestic and international destinations.
To get to Taksim Square from each airport, the fastest and best value is a shuttle run by Havataş. As of September 2016, from Atatürk Airport to Taksim, the cost is 12TL and it takes roughly 45 minutes. From Sabiha Gökçen Airport to Taksim, it’s 15TL and it takes about an hour. It’s also possible to get between Sabiha Gökçen Airport and Kadıköy in an hour for 15TL. The shuttles run roughly every 30 minutes from 4am to 1am, but traffic could seriously affect the travel times.
The metro system connects the rest of Istanbul with Atatürk Airport, and public buses connect both airports. They may be cheaper but they are much slower and not as easy to ride with all of your bags. The metro to Atatürk runs on the M1 line to Yenikapı where you can transfer to the M2 line to Taksim.
Taxi stands are also available if you’re looking for faster, more private transportation. It should cost no more than 50TL from Atatürk Airport to Taksim, but dishonest drivers have been known to charge much more exorbitant prices.