The airport is 24km from Istanbul city center.
Taxi - metered taxis are available 24/7 outside both terminals. You can use the Numbeo Istanbul Taxi Price Calculator website to get an estimate of your fare.
Bus - city buses run between Ataturk Airport, Taksim Square and the Yenikapi Fast Ferry Terminal.
Metro - the metro station is just a short walk from the terminals.
Car rental - you'll find car rental agencies in the Arrivals halls of both the Domestic and International Terminals.