The region for AST is currently observing Daylight Saving Time. The current time zone is ADT.
Please see the correct page here: Current Time in ADT.
Current Time in AST (Atlantic Standard Time)
About AST
The standard time observed in parts of eastern Canada (e.g., Nova Scotia, New Brunswick during winter), some Caribbean islands (e.g., Puerto Rico, US Virgin Islands year-round), and parts of South America. Some regions observing AST switch to ADT for daylight saving.
UTC Offset: -04:00
Current time shown is based on the representative IANA zone: America/Halifax
Atlantic Standard Time: The Complete Guide
Atlantic Standard Time (AST) is a time zone observed in the Atlantic region, primarily in the Caribbean and parts of Canada. Its standard offset is UTC-04:00, meaning it is four hours behind Coordinated Universal Time. The abbreviation AST stands for Atlantic Standard Time, and it is used year-round in many territories, while others switch to Atlantic Daylight Time (ADT) during summer months.
What Is Atlantic Standard Time?
Atlantic Standard Time (AST) is the time zone that is four hours behind Coordinated Universal Time (UTC-04:00). It is observed in the Atlantic region, including many Caribbean islands and parts of eastern Canada. The name derives from the Atlantic Ocean, which borders many of the areas that use this time zone. AST is used as standard time in most of its coverage area, but some regions observe daylight saving time, shifting to Atlantic Daylight Time (ADT), which is UTC-03:00.
Standard Offset and Daylight Saving Time
The standard offset for AST is UTC-04:00. During daylight saving time, which typically runs from the second Sunday in March to the first Sunday in November, some areas switch to ADT (UTC-03:00). However, many territories in the Caribbean do not observe daylight saving time and remain on AST year-round. For example, Puerto Rico, the U.S. Virgin Islands, and most of the Eastern Caribbean islands do not change their clocks. In Canada, the provinces of Nova Scotia, New Brunswick, Prince Edward Island, and parts of Quebec (like the Magdalen Islands) observe ADT in summer. The island of Newfoundland uses Newfoundland Standard Time (UTC-03:30) and Newfoundland Daylight Time (UTC-02:30), which is unique and not part of AST.
Regions, Countries, and Cities Covered
AST is used across a wide range of territories in the Atlantic and Caribbean. The IANA time zone database includes the following zones under AST: America/Anguilla, America/Antigua, America/Aruba, America/Barbados, America/Blanc-Sablon, America/Curacao, America/Dominica, America/Glace_Bay, America/Goose_Bay, America/Grenada, America/Guadeloupe, America/Halifax, America/Kralendijk, America/Lower_Princes, America/Marigot, America/Martinique, America/Moncton, America/Montserrat, America/Port_of_Spain, America/Puerto_Rico, America/Santo_Domingo, America/St_Barthelemy, America/St_Kitts, America/St_Lucia, America/St_Thomas. These cover the following countries and regions: Anguilla, Antigua and Barbuda, Aruba, Barbados, Canada (parts), Curaçao, Dominica, Grenada, Guadeloupe, Bonaire, Sint Eustatius and Saba, Sint Maarten (Dutch part), Saint Martin (French part), Martinique, Montserrat, Trinidad and Tobago, Puerto Rico, Saint Barthélemy, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, British Virgin Islands, U.S. Virgin Islands, Dominican Republic, Greenland (some areas), Bermuda, and more. Major cities in AST include Halifax (Canada), San Juan (Puerto Rico), Santo Domingo (Dominican Republic), Bridgetown (Barbados), Port of Spain (Trinidad and Tobago), and Hamilton (Bermuda).
How AST Differs from Neighboring Zones
AST is bordered by several other time zones. To the east, the Fernando de Noronha Time (UTC-02:00) is used in some Brazilian islands, but that is two hours ahead. To the west, Eastern Standard Time (EST, UTC-05:00) is used in the eastern United States and parts of Canada, making AST one hour ahead of EST. In South America, some areas use Amazon Time (UTC-04:00) as well, but they may not observe daylight saving. The unique Newfoundland Time Zone (UTC-03:30) is 30 minutes ahead of AST. In the Caribbean, some islands use Eastern Caribbean Time (UTC-04:00) year-round, which is essentially the same as AST but often referred to differently. The Dominican Republic uses AST year-round, while neighboring Haiti uses Eastern Standard Time (UTC-05:00) without daylight saving, creating a one-hour difference between the two countries on the island of Hispaniola.
Practical Business Hours Guidance
When scheduling across time zones, knowing AST's offset is crucial. For example, 9:00 AM in New York (EST) is 10:00 AM in AST. During daylight saving, New York is on EDT (UTC-04:00), so AST (still UTC-04:00) aligns with EDT. For calls between London (GMT/BST) and AST: London is 4 or 5 hours ahead depending on daylight saving. In winter, London (GMT) is 4 hours ahead of AST; in summer, London (BST) is 5 hours ahead. For business hours, typical working hours in AST (9:00 AM to 5:00 PM) overlap well with Eastern Time (10:00 AM to 6:00 PM EST). For Europe, a morning call in AST (8:00 AM) is noon in London (GMT) or 1:00 PM in BST. For Asia, AST is 12 hours behind Tokyo (JST, UTC+09:00), so an afternoon call in AST (2:00 PM) is 2:00 AM the next day in Tokyo, which is impractical. Best overlap for Asia is early morning AST (6:00 AM) which is 6:00 PM in Tokyo.
Frequently Asked Questions
Does Atlantic Standard Time observe daylight saving time?
Some regions do, but many do not. In Canada, provinces like Nova Scotia and New Brunswick switch to Atlantic Daylight Time (ADT, UTC-03:00) from March to November. However, most Caribbean territories, including Puerto Rico, the U.S. Virgin Islands, and many Eastern Caribbean islands, remain on AST year-round. The Dominican Republic also stays on AST all year.
What is the difference between AST and Eastern Standard Time?
AST is one hour ahead of Eastern Standard Time (EST, UTC-05:00). For example, when it is 12:00 PM EST, it is 1:00 PM AST. During daylight saving time, Eastern Daylight Time (EDT, UTC-04:00) is the same as AST, so there is no difference.
Which major cities use Atlantic Standard Time?
Major cities in AST include Halifax (Canada), San Juan (Puerto Rico), Santo Domingo (Dominican Republic), Bridgetown (Barbados), Port of Spain (Trinidad and Tobago), Hamilton (Bermuda), and Willemstad (Curaçao).
Is Atlantic Standard Time the same as Eastern Caribbean Time?
Yes, Eastern Caribbean Time (ECT) is often used informally to refer to the same offset (UTC-04:00) observed in many Caribbean islands. However, ECT is not an official IANA time zone name; the official designation is Atlantic Standard Time for most of these areas.
What is the time difference between AST and Greenwich Mean Time?
AST is 4 hours behind Greenwich Mean Time (GMT, UTC+00:00). So when it is 12:00 PM GMT, it is 8:00 AM AST. During British Summer Time (BST, UTC+01:00), the difference is 5 hours (12:00 PM BST is 7:00 AM AST).
Does Bermuda use Atlantic Standard Time?
Yes, Bermuda uses Atlantic Standard Time (UTC-04:00) during winter and Atlantic Daylight Time (UTC-03:00) during summer. Bermuda observes daylight saving time, so clocks are moved forward in March and back in November.