The calculated distance (air line) between Negombo and Sri Jayewardenepura Kotte is approximately 23 miles respectively 37 kilometers.
By car or train, the actual journey to Sri Jayewardenepura Kotte is certainly longer, as only the direct route (as the crow flies) between Negombo and Sri Jayewardenepura Kotte has been calculated here.
Air line (approximately)
37 kilometers
20 nautical miles