The calculated distance (air line) between Zürich (Kreis 9) / Altstetten and Basel is approximately 44 miles respectively 71 kilometers.
By car or train, the actual journey to Basel is certainly longer, as only the direct route (as the crow flies) between Zürich (Kreis 9) / Altstetten and Basel has been calculated here.
Air line (approximately)
71 kilometers
38 nautical miles