The calculated distance (air line) between Sancaktepe and Büyükçekmece is approximately 34 miles respectively 54 kilometers.
By car or train, the actual journey to Büyükçekmece is certainly longer, as only the direct route (as the crow flies) between Sancaktepe and Büyükçekmece has been calculated here.
Air line (approximately)
54 kilometers
29 nautical miles