How many three star officers are in the US Military?

Answer 1

Air Force, Army and Marine Corps

The United States Code explicitly limits the total number of generals that may be concurrently active to 302 for the Army, 279 for the Air Force, and 80 for the Marine Corps. For the Army and Air Force, no more than 16.3% of the service's active duty general officers may have more than two stars. Some of these slots are reserved by statute. For example, the Army and the Air Force, the Surgeon General and the Judge Advocate General for both branches are lieutenant generals. Officers serving in certain intelligence positions are not counted against either limit, including the Deputy Director of the Central Intelligence Agency. The President may also add three-star slots to one service if they are offset by removing an equivalent number from other services. Finally, all statutory limits may be waived at the President's discretion during time of war or national emergency.

http:/en.wikipedia.org/wiki/Lieutenant_general_(United_States)

Navy

U.S. Code of law explicitly limits the total number of vice admirals that may be on active duty at any given time. The total number of active-duty flag officers is capped at 216 for the Navy. For the Navy, no more than 16.3% of the service's active-duty flag officers may have more than two stars. Some of these slots are reserved by statute. For example the Surgeon General of the United States Navy is a vice admiral. The Judge Advocate General of the Navy is a vice admiral in the Navy or a lieutenant general in the Marine Corps; the Surgeon General of the United States is also vice admiral in the Public Health Service Commissioned Corps. Officers serving in certain intelligence positions are not counted against either limit, including the Deputy Director of the Central Intelligence Agency . The President may also add vice admirals to the Navy if they are offset by removing an equivalent number of three-star officers from other services. Finally, all statutory limits may be waived at the President's discretion during time of war or national emergency.

http:/en.wikipedia.org/wiki/Vice_admiral_(United_States)

Answer 2

Currently, there are 49 (VADM) three-star officers in the Navy.