AST to KST
+13hAST
ASTSOURCEKST
KSTGreen 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.
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.
KST – Korea Standard Time
UTC+09:00Korea Standard Time (KST) is the time zone for South Korea, 9 hours ahead of UTC.
- •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).
Time Conversion Guide: AST to KST
AST runs on Atlantic Standard Time (AST) at UTC-04:00. KST runs on Korea Standard Time (KST) at UTC+09:00. That puts AST 13 hours ahead of KST — a difference of +13h at the current offsets.
In practice, when it is 9:00 AM in AST it is 10:00 PM in KST. Midnight in AST is 1:00 PM in KST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
AST to KST time conversion table
| AST (AST) | KST (KST) | Day |
|---|---|---|
| 12:00 AM | 1:00 PM | same day |
| 6:00 AM | 7:00 PM | same day |
| 7:00 AM | 8:00 PM | same day |
| 8:00 AM | 9:00 PM | same day |
| 9:00 AM | 10:00 PM | same day |
| 12:00 PM | 1:00 AM | next day |
| 3:00 PM | 4:00 AM | next day |
| 5:00 PM | 6:00 AM | next day |
| 6:00 PM | 7:00 AM | next day |
| 9:00 PM | 10:00 AM | next day |
Why people convert AST to KST time
- Scheduling a call from AST to KST: a 10:00 AM start in AST lands at 11:00 PM in KST, so you can confirm the slot without doing the arithmetic yourself.
- Handling a +13h gap: AST and KST 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 KST is 10:00 PM in AST.
- Coordinating a AST-based team with KST contacts: quoting times in the other side's local clock — not your own — removes the single biggest source of missed meetings.
- 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 KST 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 KST
With a +13h offset there is no overlap inside a normal 9 AM – 5 PM day. KST 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 KST 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 KST (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
KST
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 KST?
AST (AST, UTC-04:00) is 13 hours ahead of KST (KST, UTC+09:00). The gap is currently +13h.
How do I convert AST time to KST time?
Add +13h to AST local time. For example, 9:00 AM in AST is 10:00 PM in KST.
What time is it in KST right now?
KST 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 KST 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 KST.
Which is ahead, AST or KST?
AST is 13 hours ahead of KST. When it is 12:00 PM in AST it is 1:00 AM in KST.
Does daylight saving time affect the AST–KST difference?
Neither zone observes daylight saving time, so the +13h offset between AST and KST 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 KST?
Sometimes. The +13h gap is large enough that 8:00 PM or later in AST already falls on the next day in KST.
What is the time difference between AST and KST?
KST is +13h from AST.
What timezone is AST in?
AST operates on its local timezone.
What timezone is KST in?
KST 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 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 KST?
When it is 12:00 AM (midnight) in AST (AST), it is +13h later in KST (KST).
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See every conversion from AST →·See every conversion from KST →