AEST is 10 hours ahead of Zulu, and AEDT is 11 hours ahead of Zulu. Live clocks, the full hour chart and the daylight saving rule that catches people out.
Zulu time is UTC - the clock every flight plan, order and server log is written in, precisely because it never moves. Australian Eastern Standard Time (AEST) sits UTC+10, which makes it 10 hours ahead of Zulu. Converting one to the other is a single addition, and the only two things that go wrong are the date and daylight saving.
The converter above tracks the current time until you type into it. Enter any Zulu time - 1730Z, 17:30Z or NOW - and it renders the same instant in AEST in 24-hour, 12-hour and dated form. The chart below is the same conversion for every hour of the day, so it can be read without typing anything at all.
Every hour from 0000Z to 2300Z. Two columns, because the zone has two offsets: read the AEST column in winter and the AEDT column from the first Sunday in October to the first Sunday in April. A single column here would be wrong for most of the year. Where the sum crosses midnight the date moves with it, marked in the cell.
| Zulu | AESTUTC+10 | AEDTUTC+11 |
|---|---|---|
| 0000Z | 10:00 | 11:00 |
| 0100Z | 11:00 | 12:00 |
| 0200Z | 12:00 | 13:00 |
| 0300Z | 13:00 | 14:00 |
| 0400Z | 14:00 | 15:00 |
| 0500Z | 15:00 | 16:00 |
| 0600Z | 16:00 | 17:00 |
| 0700Z | 17:00 | 18:00 |
| 0800Z | 18:00 | 19:00 |
| 0900Z | 19:00 | 20:00 |
| 1000Z | 20:00 | 21:00 |
| 1100Z | 21:00 | 22:00 |
| 1200Z | 22:00 | 23:00 |
| 1300Z | 23:00 | 00:00 +1 day |
| 1400Z | 00:00 +1 day | 01:00 +1 day |
| 1500Z | 01:00 +1 day | 02:00 +1 day |
| 1600Z | 02:00 +1 day | 03:00 +1 day |
| 1700Z | 03:00 +1 day | 04:00 +1 day |
| 1800Z | 04:00 +1 day | 05:00 +1 day |
| 1900Z | 05:00 +1 day | 06:00 +1 day |
| 2000Z | 06:00 +1 day | 07:00 +1 day |
| 2100Z | 07:00 +1 day | 08:00 +1 day |
| 2200Z | 08:00 +1 day | 09:00 +1 day |
| 2300Z | 09:00 +1 day | 10:00 +1 day |
The conversions people reach this page for, answered in one line each. The first time is AEST; the AEDT time next to it applies from the first Sunday in October to the first Sunday in April.
Take the four digits, add 10 hours, and roll the date if the result falls outside 00:00-23:59. 1730Z becomes 03:30 AEST the next day; 0200Z becomes 12:00 AEST.
Between the first Sunday in October to the first Sunday in April the zone is on Australian Eastern Daylight Time, so the correction becomes add 11 hours instead. Same instant, different local label - 1730Z is 04:30 AEDT the next day.
Controllers and forecasters often drop the minutes and write a bare hour: 16Z means 1600Z, 6Z means 0600Z. Pad it back to four digits and the chart above answers it directly.
Do the arithmetic in Zulu and convert once, at the end, for whoever needs a local time. Adding en-route time to a departure slot in local time and converting afterwards is how the day boundary gets lost. The Zulu time converter does both halves in one box.
Going the other way is the same arithmetic reversed: take the AEST time, subtract 10 hours, and write the result as four digits with a Z suffix. 22:00 AEST is 1200Z. If the sum crosses midnight the date moves too, exactly as in the chart, just in the other direction.
When the clock on the wall reads AEDT, the correction is subtract 11 hours instead: 23:00 AEDT is also 1200Z. Same instant, one hour less to undo.
Southern hemisphere, so daylight saving runs through the northern winter - October to April, the opposite of the US and Europe. Queensland does not observe it at all, so Brisbane stays on AEST while Sydney and Melbourne move to AEDT.
Zulu itself never shifts, so every hour of the shift lands on the local side of the conversion: UTC+10 in winter, UTC+11 from the first Sunday in October to the first Sunday in April. If a message does not say which, use the date it was written on to decide, and read the matching column above.
Sydney, Melbourne, Canberra and Brisbane. Almost every Zulu time converts to the next day here, which is what makes the day-shift column the one to read first.
Flight plans, METARs, TAFs, NOTAMs and ATC clearances are all in Zulu, and so are military orders, satellite passes and incident timelines. The conversion to AEST is the last step, for the people who have to be somewhere at a local hour - a briefing time, a crew report, a maintenance window. Written the aviation way it carries the day of the month too: 141730Z is the 17:30 Zulu of the 14th, which removes the last ambiguity a date shift can create. See military time for the four-digit notation itself.
The same Z closes every ISO 8601 timestamp: a log line stamped 2026-08-20T16:37:05Z happened at 1637Z, and it converts to AEST with the same arithmetic as any briefing time.
AEST is 10 hours ahead of Zulu (UTC+10). To convert, take the Zulu time and add 10 hours: 1200Z is 22:00 AEST. During Australian Eastern Daylight Time it is 23:00 AEDT instead.
The abbreviation AEST always means UTC+10, but the clock it describes switches to AEDT (UTC+11) from the first Sunday in October to the first Sunday in April. Zulu never changes, so the gap between them is an hour smaller during AEDT.
0000Z is 10:00 AEST. On daylight time it is 11:00 AEDT.
Yes, for every practical purpose. Zulu is how UTC is written and spoken in aviation and military use - the Z suffix is the phonetic letter for the zero-offset zone. GMT is the older name for the same clock reading, though the UK itself moves to BST in summer.
Reverse the arithmetic: subtract 10 hours and add the Z suffix. Do the maths in Zulu first and convert once at the end - converting first and adding afterwards is where the date boundary gets lost.
Printed from tcalc.it - free Zulu time converters, hour charts and the daylight saving rules.