The calculated distance (air line) between Castanet-Tolosan and Montpellier is approximately 119 miles respectively 192 kilometers.
By car or train, the actual journey to Montpellier is certainly longer, as only the direct route (as the crow flies) between Castanet-Tolosan and Montpellier has been calculated here.
Air line (approximately)
192 kilometers
104 nautical miles