The calculated distance (air line) between Rheinfelden and Zürich (Kreis 12) is approximately 38 miles respectively 61 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 Rheinfelden and Zürich (Kreis 12) has been calculated here.
Air line (approximately)
61 kilometers
33 nautical miles