Convert AEDT to AST

AST is 15 hours behind AEDT. AEDT is UTC+11 and AST is UTC−4.

Which AST is this?

AST names more than one zone. This page reads it as Atlantic Standard Time at UTC−4, which is the reading most converters take. There is one other: Arabia Standard Time at UTC+3, used in Saudi Arabia, Iraq, Kuwait, Bahrain, Qatar and Yemen.

The letters on a meeting invitation do not say which one is meant. If yours is not Atlantic Standard Time, the answer above is wrong, and not by a little:

The large converter sites disagree about this as well: search for a AST conversion and some of the results answer for one reading and some for another, none of them saying which they chose. Where it matters, ask which country the sender is in rather than which letters they typed.

Best time to schedule a meeting

Standard 9–5 working hours do not overlap at all between AEDT and AST. Someone has to take an early or late call — or use asynchronous communication instead.

AEDT to AST conversion table

About AEDT

Australian Eastern Daylight Time (AEDT) is UTC+11. It is used in Sydney and Melbourne from October to April.

Australian Eastern Daylight Time is UTC+11, the summer clock for Sydney, Melbourne and Canberra — and summer here means October to April, the opposite half of the year from the northern hemisphere. That inversion is what makes Australia–Europe scheduling awkward: for a few weeks each spring and autumn the two regions are shifting in opposite directions, and the offset between them changes twice within a month.

About AST

Atlantic Standard Time (AST) is UTC−4. It is used in Halifax, Puerto Rico and the eastern Caribbean in winter.

Atlantic Standard Time is UTC−4, one hour ahead of Eastern. It covers Canada's Atlantic provinces, Puerto Rico and much of the eastern Caribbean, and it is the reason a call from Halifax to Toronto is an hour out from what either party expects. The abbreviation is also used for Arabia Standard Time at UTC+3, seven hours away in the other direction, which is a genuinely dangerous collision in scheduling.

Does this gap change with the seasons?

This gap is seasonal. The abbreviations themselves are fixed offsets, but the region on AEDT switches to AEST (UTC+10) from April to October. So the 15-hour figure on this page is correct for the part of the year when both places are actually on these abbreviations, and changes by an hour outside it.

AST does not shift, so the whole change comes from one side. A recurring meeting fixed in AST will appear to move by an hour for everyone on the other side, twice a year, without anyone changing anything.

This is the reason scheduling systems store an IANA zone such as Region/City rather than an offset or an abbreviation: the zone knows its own rules and the offset does not.

Frequently asked questions

Other AEDT conversions

• AEDT to UTC
• AEDT to GMT
• AEDT to EST
• AEDT to EDT
• AEDT to CST
• AEDT to CDT
• AEDT to MST
• AEDT to MDT
• AEDT to PST
• AEDT to PDT
• AEDT to AKST
• AEDT to HST
• AEDT to BRT
• AEDT to BST
• AEDT to CET
• AEDT to CEST

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