The calculated distance (air line) between Frutigen and La Chaux-de-Fonds is approximately 53 miles respectively 85 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 Frutigen and La Chaux-de-Fonds has been calculated here.
Air line (approximately)
85 kilometers
46 nautical miles