The calculated distance (air line) between Bad Soden am Taunus and Wiesbaden is approximately 12 miles respectively 19 kilometers.
By car or train, the actual journey to Wiesbaden is certainly longer, as only the direct route (as the crow flies) between Bad Soden am Taunus and Wiesbaden has been calculated here.
Air line (approximately)
19 kilometers
10 nautical miles