The calculated distance (air line) between Brest and Saint-Pol-de-Léon is approximately 31 miles respectively 49 kilometers.
By car or train, the actual journey to Saint-Pol-de-Léon is certainly longer, as only the direct route (as the crow flies) between Brest and Saint-Pol-de-Léon has been calculated here.
Air line (approximately)
49 kilometers
27 nautical miles