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