The calculated distance (air line) between Stuttgart and La Chaux-de-Fonds is approximately 159 miles respectively 256 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 Stuttgart and La Chaux-de-Fonds has been calculated here.
Air line (approximately)
256 kilometers
138 nautical miles