The calculated distance (air line) between Bülach and La Chaux-de-Fonds is approximately 85 miles respectively 138 kilometers.
By car or train, the actual journey to La Chaux-de-Fonds is certainly longer, as only the direct route (as the crow flies) between Bülach and La Chaux-de-Fonds has been calculated here.
Air line (approximately)
138 kilometers
74 nautical miles