The calculated distance (air line) between Kampong Speu and Kampong Thom is approximately 90 miles respectively 145 kilometers.
By car or train, the actual journey to Kampong Thom is certainly longer, as only the direct route (as the crow flies) between Kampong Speu and Kampong Thom has been calculated here.
Air line (approximately)
145 kilometers
78 nautical miles