The calculated distance (air line) between Svay Rieng and Sihanoukville is approximately 158 miles respectively 254 kilometers.
By car or train, the actual journey to Sihanoukville is certainly longer, as only the direct route (as the crow flies) between Svay Rieng and Sihanoukville has been calculated here.
Air line (approximately)
254 kilometers
137 nautical miles