The calculated distance (air line) between Sauðárkrókur and Keflavík is approximately 148 miles respectively 238 kilometers.
By car or train, the actual journey to Keflavík is certainly longer, as only the direct route (as the crow flies) between Sauðárkrókur and Keflavík has been calculated here.
Air line (approximately)
238 kilometers
128 nautical miles