AST — 2 time zones
AST is used for 2 unrelated time zones. Each one is listed below with its own clock — an AST timestamp with no region attached cannot be converted safely.
Current time in AST
Arabian Standard Time
10:46
Sunday, 2 August 2026
AST = UTC+3 · 3 hours ahead of UTC
Atlantic Standard Time
03:46
Sunday, 2 August 2026
AST = UTC-4 · 4 hours behind UTC
Shown for 2 Aug 2026 07:46 UTC. The clock goes live as soon as scripts load.
UTC offsets
UTC+3 / UTC-4
Type
Standard time
Seasonal counterpart
ADT
The letters the same zones use for the other half of the year
Meanings
2
Ambiguous — always state a region
What AST can mean
Time zone abbreviations were never registered or coordinated, so the same letters were adopted independently in different parts of the world. These are the meanings in civil use, ordered by how many cities on this site use them.
| Meaning | UTC | Where |
|---|---|---|
| Arabian Standard Time | UTC+3 | Saudi Arabia, Qatar, Kuwait, Bahrain, Iraq |
| Atlantic Standard Time | UTC-4 | Canada, Dominican Republic, Puerto Rico |
Is AST in force right now?
A zone only carries this abbreviation for part of the year. This is which of them were on it at 2 Aug 2026 07:46 UTC; the list is re-derived against your own clock when scripts load.
On AST now
- Asia/Riyadh — Riyadh
- Asia/Qatar — Doha
- Asia/Kuwait — Kuwait City
- Asia/Bahrain — Manama
- Asia/Baghdad — Baghdad
- America/Santo_Domingo — Santo Domingo
- America/Puerto_Rico — San Juan
Using a different abbreviation
- America/Halifax — on ADT (UTC-3)
Atlantic Standard Time (UTC-4) alternates with ADT across the year.
Writing “AST” for a date in the other half of the year is the most common time zone mistake in meeting invitations.
Convert AST to other time zones
Arabian Standard Time (UTC+3)
Atlantic Standard Time (UTC-4)
City clocks reflect whatever their zone is doing; where a city observes daylight saving time, its difference from AST changes twice a year. Use the time zone converter for a specific date.
Time zones and cities that use AST
Arabian Standard Time · UTC+3
Atlantic Standard Time · UTC-4
Why AST is not an identifier
AST is shorthand, not a standard. There is no registry of time zone abbreviations, no authority that assigns them, and nothing preventing two regions from adopting the same three letters — which is exactly what happened here: Arabian Standard Time, Atlantic Standard Time all answer to AST.
For anything a machine will read — a calendar invitation, a database column, an API response — use the IANA identifier of the zone (Asia/Riyadh, for example) or an explicit UTC offset alongside the date. The identifier survives a change in the law; AST and its 3 hours offset do not.
Abbreviations on the same clock
Frequently asked questions
What does AST stand for?
AST has 2 meanings in civil use: Arabian Standard Time at UTC+3; Atlantic Standard Time at UTC-4. Which one is meant depends entirely on context, which is why AST should not be used where the reader cannot infer the region.
What is AST in UTC?
It depends on the meaning: Arabian Standard Time is UTC+3, Atlantic Standard Time is UTC-4. An AST timestamp with no region attached cannot be converted safely.
What is the difference between AST and ADT?
AST as Atlantic Standard Time is the standard-time form; ADT is what those same zones use during daylight saving time, one hour ahead. A summer date written "AST" is usually a mistake for ADT.
Which time zone should I use instead of AST?
Use an IANA identifier — Asia/Riyadh, Asia/Qatar and Asia/Kuwait and 2 more for Arabian Standard Time — or state the UTC offset with the date. Abbreviations are not identifiers: they are not unique, they are not registered anywhere, and half of them change with the season. Calendar software resolves this automatically when you pick a city rather than typing letters.