2230 Military Time

2230 is half past ten in the night, 10:30 PM. 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 above 12, so subtract 12 and add PM: 22 − 12 = 10.

Ten in the evening, the start of the night differential in many pay systems and of quiet hours in most units.

2230 sits 22.5 hours after midnight. A standard eight-hour shift that starts at 2230 ends at 0630 the next day; a twelve-hour shift ends at 1030 the next day.

Every single minute of this hour is listed on the 2200 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 2230 that lasts eight hours ends at 0630. For a shift with a break, the work hours calculator does the subtraction and accepts both formats.

Military to 12-hour. The hour is above 12, so subtract 12 and add PM: 22 − 12 = 10. Keep the 30 minutes: 2230 is 10:30 PM.

12-hour to military. 10 PM is a PM hour, so add 12: 10 + 12 = 22. 10:05 PM is 2205. So 10:30 PM is 2230: no colon, no PM, four digits.

The common slip is writing “22:30 PM”, which mixes the two systems. 2230 cannot be a morning time, because 22 is past 12; the morning equivalent would be 1030.

2230 is said “twenty-two thirty”. With minutes attached, the word “hundred” disappears; “twenty-two hundred thirty” is wrong, and so is “twenty-two thirty hundred”. It is the same words you would use for the number 22 followed by the number thirty.

Minutes follow the same logic. 2205 is “twenty-two zero five” and 2240 is “twenty-two forty”. Single-digit minutes get a spoken zero, so the listener knows a digit is there.

About the word “hours”: in speech, “twenty-two 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 2230”, not “at 2230 hours”.

On its own, 2230 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 2230Z 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.