The calculated distance (air line) between Monistrol-sur-Loire and Montpellier is approximately 117 miles respectively 188 kilometers.
By car or train, the actual journey to Montpellier is certainly longer, as only the direct route (as the crow flies) between Monistrol-sur-Loire and Montpellier has been calculated here.
Air line (approximately)
188 kilometers
102 nautical miles