Transportation: There are IETT buses to Taksim (number 96T). Other option is metro which goes to Aksaray. After this you can use tramway, which takes you to Sultanahmet, Eminönü, Karaköy and to Kabataş. If you want to come to Asian side you can take the tramvay until Eminönü and than boat, or you can use undersea metro line Marmaray.

Generally after 00.00 metros and buses don't operate so you can take a taxi (until Taksim or Sultanahmet it costs approx. 50TL). The bus between Taksim and aiport runs also in the night, but not very frequently.

This is public bus (IETT) schedule for winter. In summer it is much more frequent.

In order to use public transportation, you must buy a token (jeton) or (more handy) Istanbul kart. You can ask at the aiport information, where can you buy it.

You can use Istanbulkart in most of the public  transportation in Istanbul. Exceptions are taxis and dolmuşes.

Besides IETT, there is also private line HAVATAŞ (or Havaş).

If you will continue your travel with intercity bus from the main coach station (Otogar/Esenler), you can take  the metro, because the coach station is only few stops away.

If your hotel is in Sultanahmet you can go to aiport with special bus - ask at the reception of the hotel. Ticket costs 5€, but unfortunately it's only possible to use this bus to go from Sultanahmet to airport and not from airport to Sultanahmet.

Bosphorus

This airport is generally ''cheaper'' since also some low cost companies (Easyjet, Wizzair) fly there. It's quite far away from the center of Istanbul, however there is a direct bus which goes from the aiport to Kadiköy (Asian part). From Kadiköy you can reach European part by boat or another bus or Marmaray. There is also private bus company HAVAŞ which connects airpot with Kadiköy and Taksim (Europe).

If your hotel is in Sultanahmet you can go to the aiport with a special bus - ask at the reception of the hotel. (Unfortunately it's only possible to use this bus to go from Sultanahmet to airport and not from airport to Sultanahmet.)

If you are visiting Istanbul just for a few hours - maybe because you are waiting for your next flight, than you might want to join a free tour to Istanbul. Unfortunately, the tour is free only for passengers which are travelling with Turkish Airlines. Here you can see the tour schedule.

If you have any questions or need any advice before visiting Istanbul, you can contact me / post a comment under this post.

Enjoy your stay.