Istanbul and Surabaya Time Zone Comparison
Istanbul and Surabaya are two major cities that sit in noticeably different time zones. Istanbul and Surabaya sit on different continents, in noticeably different time zones, and neither observes daylight saving time.
Istanbul is always 4 hours behind Surabaya, with no seasonal change, since neither city's daylight saving rules shift this relationship.
With a moderate gap like this, it's worth checking the suggested call window above before scheduling a meeting between Istanbul and Surabaya.