The calculated distance (air line) between Solothurn and Zürich (Kreis 11) is approximately 48 miles respectively 78 kilometers.
By car or train, the actual journey to Zürich (Kreis 11) is certainly longer, as only the direct route (as the crow flies) between Solothurn and Zürich (Kreis 11) has been calculated here.
Air line (approximately)
78 kilometers
42 nautical miles