Military date format: DDMMMYY, date-time groups and Julian dates

How the military writes a date

The common US military convention, shared by allied message procedures, puts the day first, then the month as three letters, then the year. 23 October 2026 becomes one of these, depending on space and purpose:

The month abbreviations are fixed: JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV and DEC. ACP 121, the allied communication instructions, defines a date in message text this way: one or two figures for the day, the first three letters of the month and, if needed, the last two figures of the year, as in 9 JUN or 9 JUN 04.

Because the month is written in letters, it cannot be confused with the day the way it can in 10/03/26. The converter also reads DDMMMYY strings such as 23OCT26.

The date-time group (DTG)

A date-time group fixes a moment in a message. ACP 121(G) builds it from six digits followed by a zone letter: the day of the month, the hour on the 24-hour clock and the minutes. When the month and year are needed, the first three letters of the month and the last two digits of the year follow.

231430Z OCT 26 reads as:

• 23 - day of the month
• 1430 - 14:30 on the 24-hour clock
• Z - the zone letter, here UTC
• OCT 26 - October 2026

In message headers the DTG uses Z unless the theater or area commander prescribes local time, in which case the local zone letter is used. Within a message, the short form 231430Z is enough when the month and year are clear, and the full group is also written without spaces as 231430ZOCT26. ACP 121 also gives times alone as four figures and a zone letter, such as 1535Z, and advises using 2359 or 0001 instead of 2400.

Military time zone letters

ACP 121(G), Annex A to Chapter 3, assigns a letter to each 15-degree time zone. The letter tells you the correction to apply to get UTC (Greenwich Mean Time in the document).

The letter J is skipped in the ACP 121(G) table. Offsets east of Greenwich use A to M and offsets west use N to Y.

Daylight saving time moves a place one letter. ACP 121 gives Washington, DC as the example: R (UTC-5) in standard time and Q (UTC-4) in daylight time. So 14:30 UTC on 23 October 2026, when US Eastern time is on daylight time, is 231030Q OCT 26. Zones with half-hour offsets have no letter of their own; ACP 121 says to use both neighboring letters.

Military Julian dates

Supply and logistics systems use a separate numeric date: the year and the day of the year. US requisition document numbers carry a four-digit Julian date, YDDD, made of the last digit of the year and the three-digit day. 23 October 2026 is day 296, so its YDDD is 6296 and its YYDDD is 26296.

A one-digit year repeats every ten years, so 6296 can also mean 23 October 2036. Read it against the document’s other dates. The full rules, the Excel formulas and the day number of every month start are on the Julian date converter, and the 2026 Julian date calendar lists every code for the year.

Converting a DTG to local time

To turn a DTG into your local time, apply the offset of the zone letter to get UTC, then apply your own offset. 231030Q OCT 26 is 10:30 at UTC-4, which is 14:30 UTC. At UTC-7 (letter T) that is 07:30, and at UTC+1 (letter A) it is 15:30.

When the conversion crosses midnight, the day changes too: 230200Z OCT 26 is 22:00 on 22 October at UTC-4, or 222200Q OCT 26. The same UTC rules apply to the Z and offset notation of ISO 8601, covered on the ISO 8601 page.

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