The calculated distance (air line) between Sri Jayewardenepura Kotte and Kalutara is approximately 21 miles respectively 34 kilometers.
By car or train, the actual journey to Kalutara is certainly longer, as only the direct route (as the crow flies) between Sri Jayewardenepura Kotte and Kalutara has been calculated here.
Air line (approximately)
34 kilometers
18 nautical miles