Istanbul Airport (IST) is one of the largest in the world, and for a standard international-to-international connection, you should allow a minimum of 2 hours. The walking distances between gates can exceed 15–20 minutes, and security secondary checks are common. If your layover is between 6 and 24 hours and you are flying with Turkish Airlines, you are eligible for the "Touristanbul" program—a free city tour that includes transport and meals. For a layover of 20 hours or more, you might qualify for a free hotel stay under their "Stopover" program. If you intend to clear customs and visit the Blue Mosque on your own, you need at least 8 hours to account for the 60-minute commute to the historic center (Sultanahmet) and the potential for heavy Istanbul traffic. For 2026, always check if you need an e-Visa to exit the airport, as this can add 30 minutes to your transit time.