The calculated distance (air line) between Solothurn and Zürich (Kreis 12) is approximately 51 miles respectively 81 kilometers.
By car or train, the actual journey to Zürich (Kreis 12) is certainly longer, as only the direct route (as the crow flies) between Solothurn and Zürich (Kreis 12) has been calculated here.
Air line (approximately)
81 kilometers
44 nautical miles