2300 Military Time

2300 is 11:00 PM, eleven o’clock in the night. On a 24-hour clock with a colon it is 23:00; in military style the colon goes and the four digits stand alone. The hour is 23 hours after midnight and 1 hour before the next one.

Eleven in the evening, the last full hour of the day. 2359 is the last minute; the next one is 0000 of a new day.

To read it, look at the first two digits: the hour is above 12, so subtract 12 and add PM: 23 − 12 = 11. The last two digits are minutes and never change, so 2325 is 11:25 PM and 2350 is 11:50 PM.

Military to 12-hour. Split the four digits into hours and minutes, the hour is above 12, so subtract 12 and add PM: 23 − 12 = 11. So 2315 becomes 11:15 PM and 2345 becomes 11:45 PM.

12-hour to military. 11 PM is a PM hour, so add 12: 11 + 12 = 23. 11:05 PM is 2305. Drop the colon and the AM or PM, and you have the four digits.

The mistakes worth knowing: “23:00 PM” is a mix of both systems and means nothing, because a 24-hour time already says which half of the day it is. And 2300 is not 23:00 AM; there is no 23 o’clock in the morning.

2300 is said “twenty-three hundred”. The “hundred” stands in for the two zeros; nobody says “thirteen zero zero”. Numbers from ten upward are said as ordinary numbers: “twenty-three hundred”, not “one three hundred”.

Minutes follow the same logic. 2305 is “twenty-three zero five” and 2340 is “twenty-three forty”. Single-digit minutes get a spoken zero, so the listener knows a digit is there.

About the word “hours”: in speech, “twenty-three 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 2300”, not “at 2300 hours”.

On its own, 2300 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 2300Z 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.