Convert BRT to AST

AST is 1 hour behind BRT. BRT is UTC−3 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 overlap for 7 hours: 10:00 AM–5:00 PM BRT (9:00 AM–4:00 PM AST). Schedule meetings inside that window.

BRT to AST conversion table

About BRT

Brasília Time (BRT) is UTC−3. It is used in São Paulo, Rio de Janeiro and most of populated Brazil.

Brasília Time is UTC−3, covering São Paulo, Rio de Janeiro and Brasília. Brazil abolished daylight saving in 2019, so the offset is now fixed year-round — but a great deal of older software, and a lot of published advice, still assumes the southern-hemisphere shift that used to run from October to February. If a Brazilian meeting time was correct last year and is an hour out now, an out-of-date time zone database is the likely cause.

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?

Neither BRT nor AST shifts with the seasons, so this 1-hour difference holds all year. That is unusual enough to be worth relying on: most cross-continental gaps move twice a year.

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 BRT conversions

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

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