0430 Military Time

0430 is half past four in the night, 4:30 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: 4 o’clock in the morning.

Four in the morning, early enough that the hour has a joke attached to it in every barracks. It is twelve hours before 1600, the other hour people mix it up with.

0430 sits 4.5 hours after midnight. A standard eight-hour shift that starts at 0430 ends at 1230; a twelve-hour shift ends at 1630.

Every single minute of this hour is listed on the 0400 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 0430 that lasts eight hours ends at 1230. 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: 4 o’clock in the morning. Keep the 30 minutes: 0430 is 4:30 AM.

12-hour to military. 4 AM keeps its number and gains a leading zero so that it has four digits: 4:05 AM is 0405. So 4:30 AM is 0430: no colon, no AM, four digits.

The common slip is writing “04:30 AM”, which mixes the two systems. The evening counterpart of 0430 is 1630, twelve hours later.

0430 is said “zero four thirty”. With minutes attached, the word “hundred” disappears; “zero four hundred thirty” is wrong, and so is “four thirty hundred”. The leading zero is still spoken, which is what makes it sound military rather than civilian.

Minutes follow the same logic. 0405 is “zero four zero five” and 0440 is “zero four forty”. Single-digit minutes get a spoken zero, so the listener knows a digit is there.

About the word “hours”: in speech, “zero four 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 0430”, not “at 0430 hours”.

On its own, 0430 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 0430Z 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.