What is Zulu time?
Zulu time is another name for Coordinated Universal Time (UTC), the single world reference time that every time zone is measured from. When a pilot reports “departure at fourteen-thirty Zulu,” or a weather report is stamped 1430Z, it means 14:30 UTC, the same moment everywhere on Earth no matter which local time zone you’re in.
Why “Zulu”?
The world’s standard time zones were long described by their offset from the prime meridian at Greenwich, England. The zone at zero offset was labeled with the letter Z. In the NATO phonetic alphabet, used to say letters clearly over radio, Z is spoken as “Zulu.” So “Zulu time” simply means “time in the Z zone,” which is UTC.
Why aviation and the military use it
A flight from Washington to Cairo crosses seven time zones, and many countries change their clocks for daylight saving time on different dates. If every pilot, controller and weather office used local time, schedules would be a constant source of confusion and errors. Using one universal time removes the ambiguity:
- Flight plans, air traffic control and aviation weather reports (METARs and TAFs) use UTC.
- Military operations across theaters coordinate in Zulu time.
- Ships, satellites, scientific instruments, financial markets and computer systems log events in UTC.
Zulu time never changes for daylight saving time, which is exactly what makes it reliable.
Reading Zulu time
Zulu time is almost always written in 24-hour format, often with a “Z” suffix:
0600Zmeans 6:00 a.m. UTC1845Zmeans 6:45 p.m. UTC2359Zmeans one minute before midnight UTC
In the ISO 8601 date format used by computers, the Z marks a UTC timestamp, for example 2026-11-09T18:45:00Z.
The military time zone letters
The military assigns a letter to each whole-hour offset from UTC. Each letter has a phonetic name, so “Charlie time” means UTC+3.
| Letter | Name | Offset | Letter | Name | Offset |
|---|---|---|---|---|---|
| A | Alpha | UTC+1 | N | November | UTC−1 |
| B | Bravo | UTC+2 | O | Oscar | UTC−2 |
| C | Charlie | UTC+3 | P | Papa | UTC−3 |
| D | Delta | UTC+4 | Q | Quebec | UTC−4 |
| E | Echo | UTC+5 | R | Romeo | UTC−5 |
| F | Foxtrot | UTC+6 | S | Sierra | UTC−6 |
| G | Golf | UTC+7 | T | Tango | UTC−7 |
| H | Hotel | UTC+8 | U | Uniform | UTC−8 |
| I | India | UTC+9 | V | Victor | UTC−9 |
| K | Kilo | UTC+10 | W | Whiskey | UTC−10 |
| L | Lima | UTC+11 | X | X-ray | UTC−11 |
| M | Mike | UTC+12 | Y | Yankee | UTC−12 |
Z (Zulu) is UTC±0. The letter J (Juliet) is skipped in the table because it means “the observer’s local time.” For example, U.S. Eastern Standard Time (UTC−5) is Romeo time, and Eastern Daylight Time (UTC−4) is Quebec time.
Zulu time and the leap second
Because Zulu time is UTC, it follows UTC’s rules. UTC has occasionally added a “leap second” to stay in step with Earth’s rotation. In October 2026, the international body that governs units of measurement voted to stop adding leap seconds from May 20, 2027. Read more in UTC vs. GMT.
Check Zulu time now
The ZULU strip at the top of the Global Flight Clock shows the current UTC time to the second, alongside analog clocks for up to three cities.
Open the world clock →Zulu time · up to 3 cities · 12/24 h · moon phase