The calculated distance (air line) between Phnom Penh and Stung Treng is approximately 153 miles respectively 246 kilometers.
By car or train, the actual journey to Stung Treng is certainly longer, as only the direct route (as the crow flies) between Phnom Penh and Stung Treng has been calculated here.
Air line (approximately)
246 kilometers
133 nautical miles