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AST to Seoul

+13h

AST

ASTSOURCE
UTC-03:00☀ DST active
HH12
:
MM00
  
12:00 (24-hr)
12 AM6 AM12 PM6 PM12 AM

Seoul

KST
South Korea · UTC+09:00
HH01
:
MM00
  
(next day)01:00 (24-hr)
12 AM6 AM12 PM6 PM12 AM
AST
Seoul
12:00 AM
12:00 PM
2:00 AM
2:00 PM
4:00 AM
4:00 PM
6:00 AM
6:00 PM
8:00 AM
8:00 PM
10:00 AM
10:00 PM
12:00 PM
12:00 AM+1
2:00 PM
2:00 AM+1
4:00 PM
4:00 AM+1
6:00 PM
6:00 AM+1
8:00 PM
8:00 AM+1
10:00 PM
10:00 AM+1

Green rows indicate typical business hours (9 AM - 5 PM)

AST and KST on the World Map

The map below highlights the AST (Atlantic Standard Time) and KST (Korea Standard Time) timezone regions across the globe.

ASTKSTHalifaxSan JuanSanto DomingoCaracasSeoulBusanIncheonDaegu
AST Zone
→
KST Zone

Explore all world timezones interactively →

AST – Atlantic Standard Time

UTC-04:00

Atlantic Standard Time (AST) is the time zone for the Canadian Atlantic provinces and the Caribbean, 4 hours behind UTC.

Countries in AST
Canada (Atlantic provinces)Puerto RicoUS Virgin IslandsDominican RepublicVenezuelaBoliviaBarbadosTrinidad and Tobago
Major Cities in AST
HalifaxSan JuanSanto DomingoCaracasLa PazFrederictonCharlottetown
Key Facts about AST
  • •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.
Daylight Saving:Yes – switches to ADT
Learn more about AST on Wikipedia

KST – Korea Standard Time

UTC+09:00

Korea Standard Time (KST) is the time zone for South Korea, 9 hours ahead of UTC.

Countries in KST
South KoreaNorth Korea
Major Cities in KST
SeoulBusanIncheonDaeguDaejeonPyongyang
Key Facts about KST
  • •South Korea does not observe daylight saving time.
  • •Seoul is home to Samsung, LG, and Hyundai headquarters.
  • •KST is the same offset as JST (UTC+09:00).
Daylight Saving:No – UTC+09:00 year-round
Learn more about KST on Wikipedia

About Seoul

Wikipedia

Seoul operates on Korea Standard Time (KST), UTC+9, same as Japan. As a global tech and entertainment hub, Seoul coordinates with East Asian markets.

Population:9.7 million
Metro:25.5 million
Business Hours:9:00 AM - 6:00 PM KST
Currency:KRW (₩)
Stock Exchange:KRX (Korea Exchange)
Key Landmarks
Gyeongbokgung PalaceN Seoul TowerBukchon Hanok VillageDongdaemun Design PlazaCheonggyecheon Stream
Did You Know?

Seoul has the fastest average internet speed in the world.

Learn more about KST timezone →

AST vs Seoul: Offsets, DST and Best Call Times

AST runs on Atlantic Standard Time (AST) at UTC-04:00. Seoul runs on Korean Standard Time (KST) at UTC+09:00. That puts AST 13 hours ahead of Seoul — a difference of +13h at the current offsets.

In practice, when it is 9:00 AM in AST it is 10:00 PM in Seoul. Midnight in AST is 1:00 PM in Seoul. Neither zone observes daylight saving time, so the offset between them stays constant all year.

AST to Seoul time conversion table

AST (AST)Seoul (KST)Day
12:00 AM1:00 PMsame day
6:00 AM7:00 PMsame day
7:00 AM8:00 PMsame day
8:00 AM9:00 PMsame day
9:00 AM10:00 PMsame day
12:00 PM1:00 AMnext day
3:00 PM4:00 AMnext day
5:00 PM6:00 AMnext day
6:00 PM7:00 AMnext day
9:00 PM10:00 AMnext day

Why people convert AST to Seoul time

  • Scheduling a call from AST to Seoul: a 10:00 AM start in AST lands at 11:00 PM in Seoul, so you can confirm the slot without doing the arithmetic yourself.
  • Handling a +13h gap: AST and Seoul have no overlap inside a normal 9-to-5 day, so real-time meetings need an early-morning or late-evening slot on one side. 9:00 AM in Seoul is 10:00 PM in AST.
  • Watching a live event or market open: AST viewers need 10:00 PM in Seoul to catch a 9:00 AM start there, and 11:00 AM if the event is anchored to AST.
  • Always state the zone abbreviation, not just the hour. "3:00 PM AST" is unambiguous; "3 PM" across a +13h gap is not.
  • With a +13h gap there is no shared 9-to-5 window, so alternate the early start: one week AST takes the early slot, the next week Seoul does.

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 KST (Korea Standard Time)

Korea Standard Time (KST) is the time zone used in South Korea. It shares the same UTC offset as Japan Standard Time but is a distinct time zone. South Korea does not observe daylight saving time. Seoul, the capital, is a major global tech and business hub.

Best time to call between AST and Seoul

With a +13h offset there is no overlap inside a normal 9 AM – 5 PM day. Seoul opens at 9:00 AM KST, which is 10:00 PM in AST, so real-time calls need an early-morning or late-evening slot on one side.

Business hours overlap

AST and Seoul have no shared working hours because of the +13h gap. Teams need to alternate early starts or rely on asynchronous handovers.

AST is 13 hours ahead of Seoul (AST UTC-04:00 → KST UTC+09:00). There is no shared 9-to-5 window, so plan around an early or late slot. 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

Seoul

Does not observe DST

Frequently Asked Questions

What is the time difference between AST and Seoul?

AST (AST, UTC-04:00) is 13 hours ahead of Seoul (KST, UTC+09:00). The gap is currently +13h.

How do I convert AST time to Seoul time?

Add +13h to AST local time. For example, 9:00 AM in AST is 10:00 PM in Seoul.

What time is it in Seoul right now?

Seoul uses KST at UTC+09:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +13h offset from AST.

What is the best time to call Seoul from AST?

There is no shared working-hours window because of the +13h gap. The closest option is 1:00 PM in AST, which is 2:00 AM in Seoul.

Which is ahead, AST or Seoul?

AST is 13 hours ahead of Seoul. When it is 12:00 PM in AST it is 1:00 AM in Seoul.

Do AST and Seoul use different time zones?

AST uses AST at UTC-04:00, while Seoul (South Korea) uses KST at UTC+09:00. The IANA identifiers are America/Halifax and Asia/Seoul.

Does daylight saving time affect the AST–Seoul difference?

Neither zone observes daylight saving time, so the +13h offset between AST and Seoul 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 Seoul?

Sometimes. The +13h gap is large enough that 8:00 PM or later in AST already falls on the next day in Seoul.

What is the time difference between AST and Seoul?

Seoul is +13h from AST.

What timezone is AST in?

AST operates on its local timezone.

What timezone is Seoul in?

Seoul operates on Korea Standard Time (KST), UTC+9, same as Japan. As a global tech and entertainment hub, Seoul coordinates with East Asian markets.

What are the business hours in Seoul?

Standard business hours in Seoul are 9:00 AM - 6:00 PM KST.

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 KST timezone?

Major cities in the KST timezone include Seoul, Busan, Incheon, Daegu, Daejeon, Pyongyang.

What is the UTC offset for KST?

Korea Standard Time (KST) is at UTC+09:00.

What should I know about the KST timezone?

South Korea does not observe daylight saving time. Seoul is home to Samsung, LG, and Hyundai headquarters.

When is it midnight in AST, what time is it in Seoul?

When it is 12:00 AM (midnight) in AST (AST), it is +13h later in Seoul (KST).