The calculated distance (air line) between Bülach and Zürich (Kreis 3) is approximately 11 miles respectively 18 kilometers.
By car or train, the actual journey to Zürich (Kreis 3) is certainly longer, as only the direct route (as the crow flies) between Bülach and Zürich (Kreis 3) has been calculated here.
Air line (approximately)
18 kilometers
10 nautical miles