The calculated distance (air line) between Selfoss and Sauðárkrókur is approximately 131 miles respectively 212 kilometers.
By car or train, the actual journey to Sauðárkrókur is certainly longer, as only the direct route (as the crow flies) between Selfoss and Sauðárkrókur has been calculated here.
Air line (approximately)
212 kilometers
114 nautical miles