The calculated distance (air line) between La Seu d'Urgell and Lavelanet is approximately 44 miles respectively 71 kilometers.
By car or train, the actual journey to Lavelanet is certainly longer, as only the direct route (as the crow flies) between La Seu d'Urgell and Lavelanet has been calculated here.
Air line (approximately)
71 kilometers
38 nautical miles