AST — Atlantic Standard Time
See what AST means, where Atlantic Standard Time is used, how it relates to ADT, and convert it with other time zones.
Meaning and countries using AST
AST stands for Atlantic Standard Time and stays at UTC-4. It is used in places including Puerto Rico, Bermuda, Barbados, Aruba, the Dominican Republic, Trinidad and Tobago, and parts of Canada.
AST and ADT relationship
Atlantic Standard Time does not observe DST on this page’s definition, so its base offset remains UTC-4 year-round. In regions that switch seasonally, ADT is the daylight saving counterpart used in summer.
Convert AST to other zones
Compare AST with other time zones using the hour-by-hour conversion grid and scheduling table. Export meetings with ICS download or send to Google Calendar and Gmail with automatic timezone handling.
AST (Atlantic Standard Time, UTC-4) is a time zone used across parts of the Caribbean and Atlantic region for year-round scheduling, travel timing, and cross-border coordination.
Looking for Arabia Standard Time? See /time-converter/ast-arabia-time-zone.
How to Convert AST to Other Time Zones
Open the AST converter page: Go to
https://www.xconvert.com/time-converter/ast-time-zoneto load Atlantic Standard Time as the reference row in the visual comparison grid. This is useful when you are planning a call with contacts in Puerto Rico, Bermuda, or the Dominican Republic and need to compare AST against other business locations without manually counting hours.Add comparison cities: Click + Add City and search for cities you want to compare alongside Atlantic Standard Time, such as Bayamón, Basseterre, or Brades for regional coordination, or major partner locations tied to the same UTC-4 offset group. This helps remote teams, travel coordinators, and customer support managers line up working hours across Caribbean operations that share Atlantic Standard Time.
Select a time range on the grid: Click Select to enter selection mode, then drag across the AST row’s colored timeline to highlight a meeting window in purple; use the left and right handles to resize it, or drag the center to move the full range. For example, you can highlight a morning or afternoon block in Atlantic Standard Time and immediately see how that same window aligns across every added city row, which is practical for setting hotel check-in calls, cruise logistics updates, or regional sales meetings.
Export and share the schedule: Once a range is selected, use the export options for ICS download, Google Calendar, Gmail, Copy to clipboard, or Share link. That makes it easy to send a confirmed Atlantic Standard Time meeting slot to distributed teams, travel partners, or clients so everyone receives the same appointment in their own calendar workflow.
About Atlantic Standard Time (AST)
Atlantic Standard Time is the meaning of AST on this page, and its fixed offset is UTC-4. That means locations using Atlantic Standard Time are four hours behind Coordinated Universal Time, which is important for timestamping meetings, arranging regional support coverage, and coordinating transport or hospitality operations across the Caribbean.
Atlantic Standard Time is used in Anguilla, Antigua and Barbuda, Aruba, Barbados, Bermuda, Bonaire, Saint Eustatius and Saba, British Virgin Islands, Canada, Curacao, Dominica, Dominican Republic, Grenada, Guadeloupe, Martinique, Montserrat, Puerto Rico, Saint Barthelemy, Saint Kitts and Nevis, Saint Lucia, Saint Martin, Saint Vincent and the Grenadines, Sint Maarten, Trinidad and Tobago, and the U.S. Virgin Islands. This broad regional use makes Atlantic Standard Time especially relevant for island-to-island business communication, tourism scheduling, shipping coordination, and customer service teams serving multiple Caribbean markets.
Principal cities associated with Atlantic Standard Time include Baie-Mahault, Barrouallie, Basseterre, Bathsheba, Bayamón, Berekua, Bisee, Blowing Point Village, Bolands, and Brades. These places matter for practical scheduling because they represent real local markets where businesses, residents, and travelers rely on Atlantic Standard Time for flights, office hours, appointments, and event planning.
Atlantic Standard Time is a standard-time abbreviation, and its daylight saving counterpart is ADT. In practice, that means AST and ADT are not interchangeable labels: AST refers specifically to the standard-time designation, while ADT is the related daylight-time abbreviation used when a location observes that seasonal shift.
AST and Daylight Saving Time
Atlantic Standard Time is the standard-time side of the Atlantic time system, and its counterpart is Atlantic Daylight Time, abbreviated ADT. When a place uses the daylight version, the label changes from AST to ADT, so using the correct abbreviation matters for calendar invites, airline itineraries, and legal or operational timestamps.
AST itself is a standard-time abbreviation rather than a daylight-saving abbreviation. If you are coordinating with organizations across Canada, Bermuda, Puerto Rico, or the wider Caribbean, it is important to confirm whether the schedule should be written in AST or in its counterpart ADT, because the abbreviation signals which seasonal time basis is being used.
For conversion work, the key point is that Atlantic Standard Time is always written here as UTC-4. When teams use a visual comparison grid to plan meetings, they should label the selected slot with the correct abbreviation so colleagues in Atlantic-region countries can distinguish standard-time scheduling from daylight-time scheduling.
Frequently Asked Questions
What does AST stand for?
AST stands for Atlantic Standard Time on this page. It is the standard-time abbreviation for a UTC-4 time zone used across many Caribbean and Atlantic locations, including Puerto Rico, Bermuda, the Dominican Republic, and several island nations and territories.
What is the UTC offset for AST?
Atlantic Standard Time uses UTC-4. This offset is useful when comparing schedules, because any meeting, departure, or deadline listed in AST is four hours behind Coordinated Universal Time.
Is AST the same as ADT?
No, Atlantic Standard Time is not the same as ADT. AST is the standard-time abbreviation, while ADT is its daylight saving counterpart, so the two labels refer to different seasonal time designations and should not be treated as interchangeable in calendars or business communications.
Which cities use AST?
Principal cities associated with Atlantic Standard Time include Baie-Mahault, Barrouallie, Basseterre, Bathsheba, Bayamón, Berekua, Bisee, Blowing Point Village, Bolands, and Brades. These cities are useful reference points for travelers, regional businesses, and remote teams that need to align local office hours or appointment times across the Atlantic Standard Time region.
Which countries and territories use Atlantic Standard Time?
Atlantic Standard Time is used in Anguilla, Antigua and Barbuda, Aruba, Barbados, Bermuda, Bonaire, Saint Eustatius and Saba, British Virgin Islands, Canada, Curacao, Dominica, Dominican Republic, Grenada, Guadeloupe, Martinique, Montserrat, Puerto Rico, Saint Barthelemy, Saint Kitts and Nevis, Saint Lucia, Saint Martin, Saint Vincent and the Grenadines, Sint Maarten, Trinidad and Tobago, and the U.S. Virgin Islands. This wide footprint makes AST important for Caribbean tourism, regional trade, inter-island transport, and multilingual customer support operations.
When does AST change?
Atlantic Standard Time is the standard-time abbreviation, and its counterpart is ADT. When a location observes the daylight version, schedules switch from the AST label to the ADT label, so anyone booking meetings or travel should pay close attention to which abbreviation appears on the event or ticket.
Is AST Atlantic Standard Time or Arabia Standard Time?
AST can refer to more than one time-zone abbreviation, which is why the full name matters. On this page, AST means Atlantic Standard Time, which is UTC-4; the other common meaning is Arabia Standard Time, which is UTC+3, and that version is covered at /time-converter/ast-arabia-time-zone.