To convert military time to the standard 12-hour clock, subtract 12 hours from any time shown in double digits. Using this system, 13:00 is 1 p.m. and 23:00 is 11 p.m. for times between 1 and 11:59, the number stays the same and it is in the am; for those between 12 and 12:59, the number stays the same and it is in the pm. Midnight on the 24-hour system is considered to be 00:00.
Military time is used in areas where making a mistake about the time of day would be a critical mistake. Hospitals, the military, law enforcement, firefighters and paramedics all use military time to accurately keep track of the time in important situations.