AST to JST Converter & Meeting Planner
Quick answer: 9:00 AM AST = 10:00 PM JST (fixed -04:00 standard offset — not DST-adjusted). Use the interactive converter below for DST-aware local-time scheduling.
Planning a call or meeting between Atlantic Standard Time (AST) and Japan Standard Time (JST)? You need to account for the standard time difference. Japan Standard Time is normally 13 hours ahead of Atlantic Standard Time. Whether you are coordinating between teams in Halifax and San Juan and Tokyo and Osaka, our live tool has you covered. Use our interactive overlap studio below to find the perfect waking hours for both regions, taking into account any seasonal Daylight Saving Time (DST) changes.
24-Hour Conversion Table
Quick reference: 12:00 AM AST = 1:00 PM JST. The full 24-hour AST to JST table below uses fixed standard offsets for exact abbreviation searches.
Example: 3:00 PM AST = 4:00 AM JST (+1 day).
| AST Time | JST Time |
|---|---|
| 12:00 AM (00:00) | 1:00 PM (13:00) |
| 1:00 AM (01:00) | 2:00 PM (14:00) |
| 2:00 AM (02:00) | 3:00 PM (15:00) |
| 3:00 AM (03:00) | 4:00 PM (16:00) |
| 4:00 AM (04:00) | 5:00 PM (17:00) |
| 5:00 AM (05:00) | 6:00 PM (18:00) |
| 6:00 AM (06:00) | 7:00 PM (19:00) |
| 7:00 AM (07:00) | 8:00 PM (20:00) |
| 8:00 AM (08:00) | 9:00 PM (21:00) |
| 9:00 AM (09:00) | 10:00 PM (22:00) |
| 10:00 AM (10:00) | 11:00 PM (23:00) |
| 11:00 AM (11:00) | 12:00 AM (00:00)+1 day |
| 12:00 PM (12:00) | 1:00 AM (01:00)+1 day |
| 1:00 PM (13:00) | 2:00 AM (02:00)+1 day |
| 2:00 PM (14:00) | 3:00 AM (03:00)+1 day |
| 3:00 PM (15:00) | 4:00 AM (04:00)+1 day |
| 4:00 PM (16:00) | 5:00 AM (05:00)+1 day |
| 5:00 PM (17:00) | 6:00 AM (06:00)+1 day |
| 6:00 PM (18:00) | 7:00 AM (07:00)+1 day |
| 7:00 PM (19:00) | 8:00 AM (08:00)+1 day |
| 8:00 PM (20:00) | 9:00 AM (09:00)+1 day |
| 9:00 PM (21:00) | 10:00 AM (10:00)+1 day |
| 10:00 PM (22:00) | 11:00 AM (11:00)+1 day |
| 11:00 PM (23:00) | 12:00 PM (12:00)+1 day |
Best time to call Tokyo from Halifax
For most work calls, compare the normal business day in Halifax (AST) with the business day in Tokyo (JST). AST commonly covers North America, Caribbean, while JST is mainly associated with East Asia.
⚠️ Note: 2026-07-05 is not a normal workday in one or both regions based on their configured calendar. The overlap below should be treated as a reference, not a guaranteed office-hours window.
⚠️ There is no clean same-day business-hours overlap on 2026-07-05. A practical compromise is around 9:00 PM AST, which reaches 9:00 AM JST near the start of their workday.
- DST Safety: AST or JST may shift during Daylight Saving Time. Always confirm the converted time for your specific date.
- Tokyo Stock Exchange (TSE): 09:00-15:00 local time in Tokyo.
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Frequently Asked Questions
What is the time difference between AST and JST?
During standard time, Japan Standard Time is 13 hours ahead of Atlantic Standard Time.
Does the Caribbean observe Daylight Saving Time?
The vast majority of Caribbean nations and territories — including Puerto Rico, the Dominican Republic, the US Virgin Islands, Trinidad and Tobago, and Barbados — do not observe Daylight Saving Time and remain on AST (UTC-4) year-round. This means these territories share the same clock as Halifax only during the Atlantic Standard Time window in winter, diverging by one hour once Canada and Bermuda advance to ADT each spring.
What is the difference between AST and ADT?
AST (Atlantic Standard Time) is the standard winter offset at UTC-4:00, observed from the first Sunday in November through the second Sunday in March across all AST regions. ADT (Atlantic Daylight Time) is the summer offset at UTC-3:00, applied by Eastern Canadian provinces and Bermuda when they advance their clocks by one hour during Daylight Saving Time.
Does Japan observe Daylight Saving Time?
Japan has not observed Daylight Saving Time since 1951, when the practice introduced during the Allied occupation was abolished by the Japanese government. JST has remained fixed at UTC+9:00 ever since, and there is no current legislation to reintroduce DST in Japan.
Is JST the same as Korean Standard Time (KST)?
Yes, South Korea's Korean Standard Time (KST) operates at the same UTC+9:00 offset as JST, and South Korea also does not observe Daylight Saving Time. The two countries share an identical clock year-round, which simplifies scheduling for the significant trade, technology, and cultural exchange between Tokyo and Seoul.