Military time is the representation of the time of the day as a 24-hour cycle, rather than the two 12-hour cycles more commonly used. The numbers for the a.m. cycle are identical to those of common time, but where common time specifies, for instance, 3 p.m. or 11 p.m, military time represents these as 1500 or 2300. Military times of 1300 or higher can be converted to common time simply by subtracting 1200.
Military time uses four digits for all time values and doesn't use a separator character. Where a civilian writes 4:14 a.m., the military equivalent is 0414. The leading zero is also pronounced when the time is spoken; the above example is spoken as "zero four fourteen" or "oh four fourteen." When the minutes digits are zero, the suffix "hundred" is used, as in "oh nine hundred" or "fifteen hundred" for 0900 and 1500, respectively.
Military time may also include a trailing letter to indicate a time zone. In the absence of a letter, local time is assumed. Local time may also be indicated by the letter J or the word Juliet. The letter Z for "Zulu" is used to indicate Coordinated Universal Time, also known as Greenwich Mean Time.
Non-military uses of the 24-hour clock may deviate from the above, for example, by using separator characters or by dropping leading zeros. When specifying seconds or fractions of a second, a separator is always used. The time 13:31:22.04 refers to 13 hours, 31 minutes, 22 and 4/100 of a second.