The calculated distance (air line) between Le Grau-du-Roi and Montpellier is approximately 14 miles respectively 22 kilometers.
By car or train, the actual journey to Montpellier is certainly longer, as only the direct route (as the crow flies) between Le Grau-du-Roi and Montpellier has been calculated here.
Air line (approximately)
22 kilometers
12 nautical miles