The calculated distance (air line) between Dhulikhel and Siddharthanagar is approximately 128 miles respectively 207 kilometers.
By car or train, the actual journey to Siddharthanagar is certainly longer, as only the direct route (as the crow flies) between Dhulikhel and Siddharthanagar has been calculated here.
Air line (approximately)
207 kilometers
112 nautical miles