The calculated distance (air line) between Whitchurch-Stouffville and Oshawa is approximately 24 miles respectively 39 kilometers.
By car or train, the actual journey to Oshawa is certainly longer, as only the direct route (as the crow flies) between Whitchurch-Stouffville and Oshawa has been calculated here.
Air line (approximately)
39 kilometers
21 nautical miles