N18

N18 may refer to:

Roads

 * N18 road (Belgium), a National Road of Belgium
 * Route nationale 18, in France
 * N18 road (Ireland)
 * A18 motorway (Netherlands)
 * N18 (South Africa)
 * Nebraska Highway 18, in the United States

Other uses

 * BMW N18, an automobile engine
 * Chronic kidney disease
 * HMS Triumph (N18), a submarine of the Royal Navy
 * London Buses route N18
 * Nissan Almera (N18), a Japanese automobile
 * Nitrogen-18, an isotope of nitrogen
 * Tinak Airport, on Arno Atoll, Marshall Islands
 * N18, a postcode district in the N postcode area