The calculated distance (air line) between Romanshorn and La Chaux-de-Fonds is approximately 124 miles respectively 199 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 Romanshorn and La Chaux-de-Fonds has been calculated here.
Air line (approximately)
199 kilometers
108 nautical miles