The calculated distance (air line) between Rheinfelden and Zürich (Kreis 9) is approximately 34 miles respectively 55 kilometers.
By car or train, the actual journey to Zürich (Kreis 9) is certainly longer, as only the direct route (as the crow flies) between Rheinfelden and Zürich (Kreis 9) has been calculated here.
Air line (approximately)
55 kilometers
30 nautical miles