The calculated distance (air line) between Boulogne-sur-Mer and Le Havre is approximately 108 miles respectively 174 kilometers.
By car or train, the actual journey to Le Havre is certainly longer, as only the direct route (as the crow flies) between Boulogne-sur-Mer and Le Havre has been calculated here.
Air line (approximately)
174 kilometers
94 nautical miles