The calculated distance (air line) between Solothurn and Zürich (Kreis 6) is approximately 49 miles respectively 79 kilometers.
By car or train, the actual journey to Zürich (Kreis 6) is certainly longer, as only the direct route (as the crow flies) between Solothurn and Zürich (Kreis 6) has been calculated here.
Air line (approximately)
79 kilometers
42 nautical miles