AST to UTC
+4hAST
ASTSOURCEUTC
UTCGreen rows indicate typical business hours (9 AM - 5 PM)
AST and UTC on the World Map
The map below highlights the AST (Atlantic Standard Time) and UTC (Coordinated Universal Time) timezone regions across the globe.
AST – Atlantic Standard Time
UTC-04:00Atlantic Standard Time (AST) is the time zone for the Canadian Atlantic provinces and the Caribbean, 4 hours behind UTC.
- •Puerto Rico uses AST year-round and does not observe DST.
- •AST is 1 hour ahead of EST.
- •Halifax, the capital of Nova Scotia, is the largest city in AST Canada.
UTC – Coordinated Universal Time
UTC+00:00Coordinated Universal Time (UTC) is the world's primary time standard, used as the basis for civil time worldwide.
- •UTC is the basis for all civil time zones worldwide.
- •The abbreviation 'UTC' is a compromise between English (CUT) and French (TUC).
- •UTC is based on atomic clocks and is accurate to within a nanosecond per day.
- •Servers and databases worldwide store timestamps in UTC to avoid timezone confusion.
- •Leap seconds are occasionally added to UTC to keep it aligned with Earth's rotation.
Understanding the +4h Gap: AST vs UTC
AST runs on Atlantic Standard Time (AST) at UTC-04:00. UTC runs on Coordinated Universal Time (UTC) at UTC+00:00. That puts AST 4 hours ahead of UTC — a difference of +4h at the current offsets.
In practice, when it is 9:00 AM in AST it is 1:00 PM in UTC. Midnight in AST is 4:00 AM in UTC. Neither zone observes daylight saving time, so the offset between them stays constant all year.
AST to UTC time conversion table
| AST (AST) | UTC (UTC) | Day |
|---|---|---|
| 12:00 AM | 4:00 AM | same day |
| 6:00 AM | 10:00 AM | same day |
| 7:00 AM | 11:00 AM | same day |
| 8:00 AM | 12:00 PM | same day |
| 9:00 AM | 1:00 PM | same day |
| 12:00 PM | 4:00 PM | same day |
| 3:00 PM | 7:00 PM | same day |
| 5:00 PM | 9:00 PM | same day |
| 6:00 PM | 10:00 PM | same day |
| 9:00 PM | 1:00 AM | next day |
Why people convert AST to UTC time
- Scheduling a call from AST to UTC: a 10:00 AM start in AST lands at 2:00 PM in UTC, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both AST and UTC are inside the 9-to-5 working day between 9:00 AM and 1:00 PM AST time (1:00 PM–5:00 PM UTC). That is roughly 4 hours of usable overlap.
- Keeping family and friends in sync: knowing that 8:00 PM in AST is 12:00 AM in UTC makes it easy to avoid calling at 3 AM.
- Always state the zone abbreviation, not just the hour. "3:00 PM AST" is unambiguous; "3 PM" across a +4h gap is not.
- Block 9:00 AM–1:00 PM AST as the recurring meeting window if you work primarily from AST and need UTC colleagues present.
About AST (Atlantic Standard Time)
Atlantic Standard Time (AST) covers Canada's Atlantic provinces (Nova Scotia, New Brunswick, Prince Edward Island, and most of Labrador), as well as several Caribbean nations. Puerto Rico and the US Virgin Islands use AST year-round without daylight saving time. The Canadian provinces switch to Atlantic Daylight Time (ADT) in summer.
About UTC (Coordinated Universal Time)
Coordinated Universal Time (UTC) is the primary time standard by which the world regulates clocks and time. It is effectively the successor to GMT and is based on International Atomic Time with leap seconds added to keep it synchronized with Earth's rotation. UTC is used in aviation, computing, navigation, weather forecasting, and the International Space Station. Most programming languages and databases store timestamps in UTC.
Best time to call between AST and UTC
Both AST and UTC sit inside the 9 AM – 5 PM working day between 9:00 AM–1:00 PM AST, which is 1:00 PM–5:00 PM UTC. That gives roughly 4 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
AST and UTC overlap for about 4 hours during the working day — enough for meetings if you avoid the edges of the window.
AST is 4 hours ahead of UTC (AST UTC-04:00 → UTC UTC+00:00). The shared working window is 9:00 AM–1:00 PM AST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
AST
☀ Currently in DST
Standard: UTC-04:00 · DST: UTC-03:00
Clocks fall back on Sun, Nov 1, 2026
UTC
Does not observe DST
Learn More About Time
Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:
Frequently Asked Questions
What is the time difference between AST and UTC?
AST (AST, UTC-04:00) is 4 hours ahead of UTC (UTC, UTC+00:00). The gap is currently +4h.
How do I convert AST time to UTC time?
Add +4h to AST local time. For example, 9:00 AM in AST is 1:00 PM in UTC.
What time is it in UTC right now?
UTC uses UTC at UTC+00:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +4h offset from AST.
What is the best time to call UTC from AST?
Call between 9:00 AM and 1:00 PM AST — that maps to 1:00 PM–5:00 PM UTC and keeps both parties inside the working day.
Which is ahead, AST or UTC?
AST is 4 hours ahead of UTC. When it is 12:00 PM in AST it is 4:00 PM in UTC.
Does daylight saving time affect the AST–UTC difference?
Neither zone observes daylight saving time, so the +4h offset between AST and UTC is fixed all year.
Which other cities share AST's time zone?
AST also covers Halifax, San Juan, Santo Domingo, Caracas, La Paz, Fredericton, Charlottetown.
Which countries use AST, AST's zone?
AST is used in Canada (Atlantic provinces), Puerto Rico, US Virgin Islands, Dominican Republic, Venezuela, Bolivia, Barbados, Trinidad and Tobago.
Is there a day difference between AST and UTC?
Not normally. The +4h gap only pushes the date over for late-evening times.
What is the time difference between AST and UTC?
UTC is +4h from AST.
What timezone is AST in?
AST operates on its local timezone.
What timezone is UTC in?
UTC operates on its local timezone.
Which countries use AST (Atlantic Standard Time)?
AST is used in Canada (Atlantic provinces), Puerto Rico, US Virgin Islands, Dominican Republic, Venezuela, Bolivia, and 2 more countries.
Does AST observe daylight saving time?
Yes, AST switches to ADT during summer months.
What are some interesting facts about AST?
Puerto Rico uses AST year-round and does not observe DST. AST is 1 hour ahead of EST.
Which cities are in the UTC timezone?
Major cities in the UTC timezone include London, Dublin, Reykjavik, Accra, Lisbon, Dakar.
What is the UTC offset for UTC?
Coordinated Universal Time (UTC) is at UTC+00:00.
What should I know about the UTC timezone?
UTC is the basis for all civil time zones worldwide. The abbreviation 'UTC' is a compromise between English (CUT) and French (TUC).
When is it midnight in AST, what time is it in UTC?
When it is 12:00 AM (midnight) in AST (AST), it is +4h later in UTC (UTC).
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See every conversion from AST →·See every conversion from UTC →