The calculated distance (air line) between Brno and Jablonec nad Nisou is approximately 123 miles respectively 199 kilometers.
By car or train, the actual journey to Jablonec nad Nisou is certainly longer, as only the direct route (as the crow flies) between Brno and Jablonec nad Nisou has been calculated here.
Air line (approximately)
199 kilometers
107 nautical miles