The calculated distance (air line) between Zürich (Kreis 4) / Hard and Winterthur is approximately 13 miles respectively 21 kilometers.
By car or train, the actual journey to Winterthur is certainly longer, as only the direct route (as the crow flies) between Zürich (Kreis 4) / Hard and Winterthur has been calculated here.
Air line (approximately)
21 kilometers
11 nautical miles