The U.S. Navy has a total of 26 possible ranks, ranging from seaman recruit to fleet admiral. While fleet admiral is the highest possible rank in the Navy, it exists during wartime only. The current highest rank as of 2015 is admiral chief of naval operations/commandant of the Coast Guard.
The three fundamental grades of naval ranks are enlisted, warrant officers and officers, labeled with the abbreviations E, W and O. Individual ranks line up within each of these grades. For example, E-1 refers to a seaman recruit, and E-2 to a seaman apprentice. The remaining enlisted ranks are seaman, petty officer third class, petty officer second class and petty officer first class. After that comes chief petty officer, senior chief petty officer, master chief petty officer, fleet/commander master chief petty officer and master chief petty officer of the Navy.
The next category is that of the warrant officers. The warrant officer ranks run from chief warrant officer 2 to chief warrant officer 5.
The highest grade is that of the naval officers. The lowest officer rank is ensign, followed by lieutenant junior grade, lieutenant and lieutenant commander. The next are commander, and then captain, followed by rear admiral (lower half) and rear admiral (upper half). Vice admiral is currently the second-highest rank in the U.S. Navy.
Officers in the U.S. Military wear insignia, or rank devices, on their uniforms to display their ranks. The Navy is unique because rank devices differ depending on which of three uniforms the officer wears. For khakis, a working uniform, rank is displayed by pins on the collar. Blues and whites are both dress uniforms. On blues, the rank device is stripes sewn on the lower sleeve, while the rank device for whites is stripes on shoulder boards.