The calculated distance (air line) between Adalar and Büyükçekmece is approximately 30 miles respectively 49 kilometers.
By car or train, the actual journey to Büyükçekmece is certainly longer, as only the direct route (as the crow flies) between Adalar and Büyükçekmece has been calculated here.
Air line (approximately)
49 kilometers
26 nautical miles