0630 Military Time

0630 is half past six in the early morning, 6:30 AM. The first two digits are the hour, the last two are the minutes, and the minutes are the same in every system: 30 stays 30. Only the hour needs attention: the hour is below 12, so drop the leading zero and add AM: 6 o’clock in the morning.

Six in the morning, the first hour that lines up with ordinary shift language: 0600 to 1400 is an early shift, 0600 to 1800 is a twelve.

0630 sits 6.5 hours after midnight. A standard eight-hour shift that starts at 0630 ends at 1430; a twelve-hour shift ends at 1830.

Every single minute of this hour is listed on the 0600 page.

Adding whole hours to military time is a plain sum until you pass 2359, then you subtract 24 and move to the next day. A shift from 0630 that lasts eight hours ends at 1430. For a shift with a break, the work hours calculator does the subtraction and accepts both formats.

Military to 12-hour. The hour is below 12, so drop the leading zero and add AM: 6 o’clock in the morning. Keep the 30 minutes: 0630 is 6:30 AM.

12-hour to military. 6 AM keeps its number and gains a leading zero so that it has four digits: 6:05 AM is 0605. So 6:30 AM is 0630: no colon, no AM, four digits.

The common slip is writing “06:30 AM”, which mixes the two systems. The evening counterpart of 0630 is 1830, twelve hours later.

0630 is said “zero six thirty”. With minutes attached, the word “hundred” disappears; “zero six hundred thirty” is wrong, and so is “six thirty hundred”. The leading zero is still spoken, which is what makes it sound military rather than civilian.

Minutes follow the same logic. 0605 is “zero six zero five” and 0640 is “zero six forty”. Single-digit minutes get a spoken zero, so the listener knows a digit is there.

About the word “hours”: in speech, “zero six hundred hours” is everywhere, and nobody will correct you. In writing, Army Regulation 25-50 says the word is not used with military time, so a memorandum reads “at 0630”, not “at 0630 hours”.

On its own, 0630 is local time wherever it is written. When the four digits carry a letter, the letter is the time zone. Z stands for Zulu, which is UTC, and J (Juliet) means the local time of the person speaking. The table converts 0630Z to the four US zones, in standard time and in daylight saving time.

Eastern Time is four hours behind UTC from March to November and five hours behind the rest of the year, which is why one Zulu time maps to two possible local times. The other three zones follow the same pattern an hour further west each.

Midnight has a second spelling, 2400, used when it marks the end of a day rather than the start. The full rules, with a converter, are on the military time chart page.