The calculated distance (air line) between Rishon LeTsiyyon and Modiin Ilit is approximately 15 miles respectively 24 kilometers.
By car or train, the actual journey to Modiin Ilit is certainly longer, as only the direct route (as the crow flies) between Rishon LeTsiyyon and Modiin Ilit has been calculated here.
Air line (approximately)
24 kilometers
13 nautical miles