KST to AST Converter
Convert time between Korea Standard Time (KST) and Atlantic Standard Time (AST)
Korea Standard Time (KST)
Atlantic Standard Time (AST)
Time Difference
Atlantic Standard Time (AST) is 0 hours ahead of Korea Standard Time (KST)
Select Date
Select Time
Quick Reference
| KST | AST |
|---|---|
| 11:00 | 23:00 |
| 13:00 | 01:00 |
| 15:00 | 03:00 |
| 17:00 | 05:00 |
| 19:00 | 07:00 |
| 21:00 | 09:00 |
| 23:00 | 11:00 |
| 01:00 | 13:00 |
| 03:00 | 15:00 |
| 05:00 | 17:00 |
| 07:00 | 19:00 |
| 09:00 | 21:00 |
Top 10 Most Common Time Zones
| Abbreviation | Full Name | UTC Offset | Typical Use |
|---|---|---|---|
| UTC | Coordinated Universal Time | UTC ±0 | Global reference standard (servers, logs, APIs) |
| EST / EDT | Eastern (US) Time | UTC −5 / −4 | New York, Toronto — North American business hub |
| CST / CDT | Central (US) Time | UTC −6 / −5 | Chicago, Dallas — US central business region |
| PST / PDT | Pacific (US) Time | UTC −8 / −7 | San Francisco, Los Angeles — tech industry standard |
| GMT / BST | Greenwich Mean / British Summer Time | UTC 0 / +1 | UK, used globally as a reference with UTC |
| CET / CEST | Central European (Summer) Time | UTC +1 / +2 | Paris, Berlin, Amsterdam — EU business core |
| IST | India Standard Time | UTC +5:30 | India — major IT & outsourcing region |
| CST | China Standard Time | UTC +8 | Beijing, Shanghai — East Asia business hub |
| JST | Japan Standard Time | UTC +9 | Tokyo — finance & tech hub |
| AEST / AEDT | Australian Eastern (Daylight) Time | UTC +10 / +11 | Sydney, Melbourne — APAC regional business |
Why Time Zone Abbreviations Are Ambiguous
Unlike standardized identifiers (like America/New_York or Europe/London from the IANA tz database), abbreviations such as "CST" or "IST" are not globally unique. They can refer to different time zones depending on context — country, region, or even time of year (due to daylight saving time).
Common Ambiguous Time Zone Abbreviations
| Abbrev. | Common Meaning(s) | UTC Offset | Region(s) |
|---|---|---|---|
| CST | Central Standard Time / China Standard Time / Cuba Standard Time | UTC−6 / UTC+8 / UTC−5 | North America, China, Cuba |
| IST | Indian Standard Time / Irish Standard Time / Israel Standard Time | UTC+5:30 / UTC+1 / UTC+2 | India, Ireland, Israel |
| AST | Atlantic Standard Time / Arabia Standard Time | UTC−4 / UTC+3 | Caribbean, Canada, Middle East |
| PST | Pacific Standard Time / Philippine Standard Time | UTC−8 / UTC+8 | North America, Philippines |
| EST | Eastern Standard Time (North America / Australia) | UTC−5 / UTC+10 | North America, Australia |
✅ Best Practice
To avoid ambiguity, always:
- Use IANA tz identifiers — e.g.,
America/New_Yorkinstead of "EST" - Specify UTC offset explicitly — e.g.,
UTC−5when abbreviations must be used - Include the full timezone name — e.g., "Eastern Standard Time (EST)" with UTC offset
About KST to AST Time Conversion
Converting time from Korea Standard Time (KST) to Atlantic Standard Time (AST) is essential for South Korea-eastern Canada coordination. KST is UTC+9 and AST is UTC-4, making KST 13 hours ahead of AST. South Korea does not observe daylight saving time.
Atlantic Canada switches to ADT (UTC-3) from the second Sunday in March to the first Sunday in November, dropping the gap to 12 hours. This converter uses the IANA timezone database (America/Halifax) to apply the correct offset automatically based on the date you pick.
Common Use Cases for KST to AST Conversion
Business & Work
- Scheduling calls between Korean teams and Halifax, Saint John, or St. John's offices
- Coordinating shipping or fisheries operations between South Korea and Atlantic Canada
- Planning project handoffs across the Pacific and North America
Personal & Travel
- Keeping in touch with family or friends in Atlantic Canada
- Planning travel from South Korea to Halifax, Saint John, or St. John's
- Scheduling virtual events that span Asia and North America
Time Zone Information
Korea Standard Time (KST)
- UTC Offset: UTC+9 (no DST observed)
- IANA Timezone: Asia/Seoul
- Daylight Saving: South Korea does not observe daylight saving time
- Major Cities: Seoul, Busan, Incheon, Daegu, Daejeon, Gwangju, Jeju
- Coverage: All of South Korea
Atlantic Standard Time (AST)
- UTC Offset: UTC-4 (UTC-3 ADT during DST)
- IANA Timezone: America/Halifax
- Daylight Saving: Second Sunday in March to First Sunday in November
- Major Cities: Halifax, Saint John, Charlottetown, Moncton
- Coverage: Atlantic Canada: Nova Scotia, New Brunswick, Prince Edward Island, and parts of Labrador (Newfoundland uses NST/NDT)
Quick Reference: KST to AST
Remember: AST is 13 hours behind KST; during ADT the gap drops to 12 hours
Frequently Asked Questions
What is the time difference between KST and AST?
Korea Standard Time (KST) is UTC+9, while Atlantic Standard Time (AST) is UTC-4. KST is 13 hours ahead of AST, so when it is 12:00 PM Monday in Seoul, it is 11:00 PM Sunday in Halifax.
When does AST apply versus ADT?
AST runs from the first Sunday in November to the second Sunday in March. Outside that window, Atlantic Canada uses ADT (UTC-3), which is 12 hours behind KST. Korea does not observe DST.
Is the date always different between Korea and Atlantic Canada?
Often, yes. With KST 13 hours ahead of AST, mornings in Korea correspond to the previous evening in Atlantic Canada — late evenings in Korea are pre-dawn the same day in Halifax.
What are the best times to schedule KST to AST business calls?
Live overlap is limited. A workable bridge is early morning Korea (8–10 AM KST), which is 7–9 PM AST the previous day — fine for end-of-day Atlantic calls. Otherwise, asynchronous handoffs are often more practical.
Which regions and cities use AST?
AST (UTC-4) covers Atlantic Canada — Nova Scotia, New Brunswick, Prince Edward Island, and parts of Labrador. Major cities include Halifax, Saint John, Charlottetown, and Moncton. Newfoundland uses NST/NDT instead.
Which regions use KST?
KST (UTC+9) is used by all of South Korea. Major cities include Seoul, Busan, Incheon, Daegu, Daejeon, Gwangju, and Jeju. South Korea does not observe daylight saving time.
Pro Tips
- • AST is 13 hours behind KST — subtract 13 hours from Korean time, and adjust the date if needed.
- • AST applies only during Atlantic Canada's winter (early November to mid-March); use ADT and a 12-hour gap the rest of the year.
- • Korea never observes DST, so all seasonal change is on the Canadian side.
- • For live calls, early-morning Korea (8–10 AM KST) lines up with late-evening Atlantic Canada the previous day (7–9 PM AST).
- • For recurring meetings, fix the Atlantic Canadian local time and let KST shift automatically with ADT/AST transitions.
- • Newfoundland is 30 minutes ahead of AST/ADT — if your contact is in St. John's, add 30 minutes to the Atlantic time.