The calculated distance (air line) between Ísafjörður and Mosfellsbær is approximately 138 miles respectively 223 kilometers.
By car or train, the actual journey to Mosfellsbær is certainly longer, as only the direct route (as the crow flies) between Ísafjörður and Mosfellsbær has been calculated here.
Air line (approximately)
223 kilometers
120 nautical miles