|Country||United States of America|
|NATO rank code||OF-5|
|Next higher rank||Rear admiral (lower half)|
|Next lower rank||Commander|
|Equivalent ranks||Colonel (United States Army, Marine Corps, Space Force and Air Force)|
In the United States Navy, United States Coast Guard, United States Public Health Service Commissioned Corps (USPHS), and National Oceanic and Atmospheric Administration Commissioned Officer Corps (NOAA Corps), captain is the senior-most commissioned officer rank below that of flag officer (i.e., admirals). The equivalent rank is colonel in the United States Army, Air Force, Space Force, and Marine Corps.
Reflecting its nautical heritage, the term captain is used as a military title by more junior officers who command a commissioned vessel of the Navy, Coast Guard, or National Oceanic and Atmospheric Administration ship of patrol boat size or greater. Officers below O-6 who command aviation squadrons (typically O-5 commanders) usually use the less formal title "skipper".
The United States Coast Guard also uses the same naval rank system for its commissioned officers as the U.S. Navy, with a Coast Guard captain ranking above a commander and below rear admiral (lower half). The sleeve and shoulder board insignia are similar to the Navy insignia, with a lighter shade of blue with a gold USCG shield above the stripes. Coast Guard captains follow career paths very similar to their Navy counterparts, with marine safety, security, and boat forces officers serving as Captain of the Port in command of Coast Guard Sectors, seagoing officers typically commanding large maritime security cutters or high endurance cutters and aviators commanding Coast Guard air stations. Coast Guard captains will also command all types of major Coast Guard shore installations and activities, as well as serve as chiefs of staff / executive assistants, senior operations officers, and other senior staff officers for Coast Guard flag officers. The Coast Guard has no staff corps officers.
Like the U.S. Navy, all commanding officers of commissioned cutters (e.g., USCGC or "United States Coast Guard Cutter") are addressed as "captain" regardless of their actual rank.
In the United States Public Health Service (USPHS), and in the National Oceanic and Atmospheric Administration Commissioned Officer Corps, captains are senior non-combatant officers that serve as directors or ranking supervisors in their respective uniformed service corps. Seagoing NOAA captains command certain National Oceanic and Atmospheric Administration (NOAA) ships, while NOAA aviators command NOAA flight operations activities. USPHS rapid deployment force teams, containing 105 USPHS physicians, nurses, and other medical professionals, are commanded exclusively by captains.
Although it exists largely as a maritime training organization, the United States Maritime Service also uses the rank of captain. Even though the Maritime Service is an auxiliary service, the grade is appointed by the President via the Secretary of Transportation, making it a federally recognized rank with corresponding paygrade of O-6.