The calculated distance (air line) between Şişli and Büyükçekmece is approximately 21 miles respectively 34 kilometers.
By car or train, the actual journey to Büyükçekmece is certainly longer, as only the direct route (as the crow flies) between Şişli and Büyükçekmece has been calculated here.
Air line (approximately)
34 kilometers
18 nautical miles