Military time zone letters.

How the military time zone letters work

The military system gives each one-hour slice of the world a letter. Z, spoken "Zulu", is Coordinated Universal Time (UTC), the reference every other letter is measured from. Moving east, the letters run A (UTC+1) through I (UTC+9), skip J, and continue with K (UTC+10), L (UTC+11) and M (UTC+12). Moving west they run N (UTC-1) through Y (UTC-12). That is where "alpha bravo charlie time zones" come from: Alfa is one hour ahead of Zulu, Bravo two, Charlie three, and so on. The chart below follows the table in Wikipedia's list of military time zones, which cites ACP 121(I), the Combined Communications-Electronics Board's communication instructions.

Military time zone chart

The "standard-time examples" column shows places on that offset in winter or all year round. Letters never move with daylight saving time. In summer, New York is on UTC-4, which is Quebec, not Romeo.

Worked example (hypothetical)

A message says a convoy leaves at 1500R. R is Romeo, UTC-5, so 15:00 in zone R equals 15:00 + 5 hours = 20:00 Zulu, written 2000Z. Another message gives 0300A. A is UTC+1, so Zulu is 03:00 - 1 hour = 02:00, written 0200Z. West of Zulu you add the offset to get Zulu; east of Zulu you subtract it. When the arithmetic crosses midnight the calendar date changes too, which is why a full date-time group carries a day number (see the DTG formatter).

The letters people get wrong

J (Juliett) is not a zone. It stands for the local time of whoever is writing, so 1200J means noon wherever the sender is. There is no UTC offset to convert from. L is not "local". L is UTC+11. Some editions of the US Army's FM 5-0 misused L for local time, and Wikipedia notes the May 2022 edition corrected that. M and Y are the two ends of the date line: both show the same clock time, but M (UTC+12) is a calendar day ahead of Y (UTC-12). N normally means UTC-1, but the same Wikipedia list records that N is also used for "zone -13" (UTC+13) so a ship in zone -12 can keep daylight saving time. This lookup treats N as UTC-1 and flags the exception. The system also has no half-hour zones: India (UTC+5:30) and Nepal (UTC+5:45) fall between letters, so the tool names the neighbouring pair instead of guessing.

Military time zone letters in email headers

You may see a letter where an email's Date: header normally has +0000 or -0500. RFC 2822 section 4.3 says the one-character military zones were defined in a non-standard way in RFC 822 and are therefore unpredictable in their meaning. It lists the original mapping (A to I as +0100 to +0900, K to M as +1000 to +1200, N to Y as -0100 to -1200, Z as +0000) and then says that, because of the RFC 822 error, receivers SHOULD treat all of them as equivalent to -0000 unless out-of-band information confirms their meaning. In practice that means the instant is UTC with the sender's local zone unknown. Software that generates mail should write a numeric offset, never a letter.

Who this is for

Pilots and sailors checking a message, emergency and disaster-response volunteers, military families and cadets, game and fiction writers who want accurate "zero-six-hundred Zulu" detail, and developers who meet a letter zone in a log or email header and need to know what it means.

What this does not cover

It does not give legal or operational guidance, and it does not replace the orders or publication your unit uses. It uses fixed standard-time offsets, ignores daylight saving rules, and does not know any country's current civil time. For a named place, use a time zone tool that knows the rules, such as the meeting planner. To convert a specific moment, use the Zulu time converter. To spell the letter names aloud, see the NATO phonetic alphabet.

FAQ

What are the military time zone letters?

Each one-hour slice of the world has a letter: A to I are UTC+1 to UTC+9, K to M are UTC+10 to UTC+12, N to Y are UTC-1 to UTC-12, and Z is UTC itself. J is skipped and means the writer's local time.

What time zone is Romeo?

Romeo (R) is UTC-5, the offset of Eastern Standard Time, for example New York or Toronto in winter. In summer those cities are on UTC-4, which is Quebec (Q).

What are the alpha bravo charlie time zones?

Alfa (A) is UTC+1, Bravo (B) UTC+2, Charlie (C) UTC+3, Delta (D) UTC+4, and so on through India (I) at UTC+9. The letters are the NATO phonetic words for the zone letter.

Why is there no J time zone?

J is not a fixed zone. It means the local time of the person giving the time, so it has no UTC offset. The Wikipedia list says it was originally skipped and may be used for the observer's local time.

Is L the military letter for local time?

No. L is UTC+11. Local time is J. Some editions of US Army FM 5-0 misused L for local, and the May 2022 edition corrected it.

What is the difference between M and Y?

Both are 12 hours from UTC, so they show the same clock time, but M (UTC+12) is one calendar day ahead of Y (UTC-12).

What do military time zone letters mean in an email header?

RFC 2822 says they were defined inconsistently in RFC 822 and receivers SHOULD treat them as -0000 (UTC, local zone unknown) unless other information confirms the meaning. Senders should use numeric offsets.

Do military time zones change with daylight saving time?

No. A letter is a fixed offset from UTC. A place that moves to daylight time simply uses the letter one step east, so New York changes from R to Q.

Sources (each opened 2026-10-20): Wikipedia, List of military time zones (cites ACP 121(I), CCEB, October 2010); RFC 2822, Internet Message Format, section 4.3 (obsolete date and time). ACP 121 itself is not freely downloadable, so the letter table is taken from the Wikipedia list that cites it; check your unit's own publication for operational use.