The calculated distance (air line) between La Seu d'Urgell and Puigcerdà is approximately 24 miles respectively 39 kilometers.
By car or train, the actual journey to Puigcerdà is certainly longer, as only the direct route (as the crow flies) between La Seu d'Urgell and Puigcerdà has been calculated here.
Air line (approximately)
39 kilometers
21 nautical miles