Istanbul is 2 hours ahead of Berlin (or 1 hour during CEST). Berlin uses Central European Time (CET/CEST, UTC+1/+2) while Istanbul uses Turkey Time (TRT, UTC+3). When it's 12:00 PM in Berlin, it's 2:00 PM in Istanbul (or 1:00 PM during Berlin's daylight saving time).
Berlin observes daylight saving time while Turkey does not, so the difference varies between 1 and 2 hours throughout the year.
Best calling time: 7:00 AM - 4:00 PM Berlin time. This corresponds to 9:00 AM - 6:00 PM in Istanbul, covering standard business hours.
Berlin and Istanbul have deep historical and modern connections. Germany has a large Turkish diaspora, and there are strong business ties between the countries. Direct flights connect the cities in about 3 hours, making this one of Europe's busiest routes.