The calculated distance (air line) between Stung Treng and Siem Reap is approximately 142 miles respectively 229 kilometers.
By car or train, the actual journey to Siem Reap is certainly longer, as only the direct route (as the crow flies) between Stung Treng and Siem Reap has been calculated here.
Air line (approximately)
229 kilometers
123 nautical miles