The term Atlantic Time (AT) is often used to denote the local time in areas observing either Atlantic Standard Time (AST) or Atlantic Daylight Time (ADT).
In other words, in locations observing Daylight Saving Time during part of the year, Atlantic Time is not static but switches between AST and ADT.
Atlantic Time UTC Offset
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Atlantic Standard Time is 4 hours behind Coordinated Universal Time.
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Atlantic Daylight Time is 3 hours behind Coordinated Universal Time.
What Is Atlantic Time?
Atlantic Time (AT) is an eastern time zone in North America. It is used in the northeast of Canada and the US territories Puerto Rico and the US Virgin Islands.
It is not currently used in mainland United States.
In North America, Atlantic Time shares a border with Eastern Time (ET) in the west.
What Does AT Time Zone Mean?
Unlike other time zone denominations, which have a fixed time, Atlantic Time refers to a geographical area where the time changes twice yearly as Daylight Saving Time (DST) begins and ends. Atlantic Standard Time is UTC-4, while Atlantic Daylight Time is UTC-3.
Most North American time zones have generic terms, including Pacific Time (PT), Mountain Time (MT), Central Time (CT), and Eastern Time (ET).
Converting Atlantic Time to Other US Time Zones
- Atlantic Time (AT) is 1 hour ahead of Eastern Time (ET).
To convert AT to ET, you have to subtract one hour. - Atlantic Time (AT) is 2 hours ahead of Central Time (CT).
To convert AT to CT, you have to subtract two hours. - Atlantic Time (AT) is 3 hours ahead of Mountain Time (MT).
To convert AT to MT, you have to subtract three hours. - Atlantic Time (AT) is 4 hours ahead of Pacific Time (PT).
To convert AT to PT, you have to subtract four hours.
Where and When is AT Observed?
North America
Caribbean
Caribbean countries/territories using AST all year round
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Caribbean NetherlandsBonaire, Sint Eustatius, Saba