The calculated distance (air line) between Phnom Penh and Smach Mean Chey is approximately 127 miles respectively 205 kilometers.
By car or train, the actual journey to Smach Mean Chey is certainly longer, as only the direct route (as the crow flies) between Phnom Penh and Smach Mean Chey has been calculated here.
Air line (approximately)
205 kilometers
111 nautical miles