The calculated distance (air line) between Saint-Martin-de-Crau and Montpellier is approximately 47 miles respectively 75 kilometers.
By car or train, the actual journey to Montpellier is certainly longer, as only the direct route (as the crow flies) between Saint-Martin-de-Crau and Montpellier has been calculated here.
Air line (approximately)
75 kilometers
41 nautical miles