The calculated distance (air line) between Schwalbach am Taunus and Wiesbaden is approximately 13 miles respectively 22 kilometers.
By car or train, the actual journey to Wiesbaden is certainly longer, as only the direct route (as the crow flies) between Schwalbach am Taunus and Wiesbaden has been calculated here.
Air line (approximately)
22 kilometers
12 nautical miles