IST to AST Converter & Meeting Planner
Quick answer: 9:00 AM IST = 11:30 PM AST (fixed +05:30 standard offset — not DST-adjusted). Use the interactive converter below for DST-aware local-time scheduling.
Planning a call or meeting between Indian Standard Time (IST) and Atlantic Standard Time (AST)? You need to account for the standard time difference. Atlantic Standard Time is normally 9.5 hours behind Indian Standard Time. Whether you are coordinating between teams in Mumbai and New Delhi and Halifax and San Juan, 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 IST = 2:30 PM AST. The full 24-hour IST to AST table below uses fixed standard offsets for exact abbreviation searches.
Example: 3:00 PM IST = 5:30 AM AST.
| IST Time | AST Time |
|---|---|
| 12:00 AM (00:00) | 2:30 PM (14:30)-1 day |
| 1:00 AM (01:00) | 3:30 PM (15:30)-1 day |
| 2:00 AM (02:00) | 4:30 PM (16:30)-1 day |
| 3:00 AM (03:00) | 5:30 PM (17:30)-1 day |
| 4:00 AM (04:00) | 6:30 PM (18:30)-1 day |
| 5:00 AM (05:00) | 7:30 PM (19:30)-1 day |
| 6:00 AM (06:00) | 8:30 PM (20:30)-1 day |
| 7:00 AM (07:00) | 9:30 PM (21:30)-1 day |
| 8:00 AM (08:00) | 10:30 PM (22:30)-1 day |
| 9:00 AM (09:00) | 11:30 PM (23:30)-1 day |
| 10:00 AM (10:00) | 12:30 AM (00:30) |
| 11:00 AM (11:00) | 1:30 AM (01:30) |
| 12:00 PM (12:00) | 2:30 AM (02:30) |
| 1:00 PM (13:00) | 3:30 AM (03:30) |
| 2:00 PM (14:00) | 4:30 AM (04:30) |
| 3:00 PM (15:00) | 5:30 AM (05:30) |
| 4:00 PM (16:00) | 6:30 AM (06:30) |
| 5:00 PM (17:00) | 7:30 AM (07:30) |
| 6:00 PM (18:00) | 8:30 AM (08:30) |
| 7:00 PM (19:00) | 9:30 AM (09:30) |
| 8:00 PM (20:00) | 10:30 AM (10:30) |
| 9:00 PM (21:00) | 11:30 AM (11:30) |
| 10:00 PM (22:00) | 12:30 PM (12:30) |
| 11:00 PM (23:00) | 1:30 PM (13:30) |
Best time to call Halifax from Mumbai
For most work calls, compare the normal business day in Mumbai (IST) with the business day in Halifax (AST). IST commonly covers South Asia, while AST is mainly associated with North America, Caribbean.
⚠️ 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.
✅ The most practical overlap on 2026-07-05 is usually 5:30 PM - 6:30 PM IST, which corresponds to 9:00 AM - 10:00 AM AST. This window sits inside the typical IST workday (9:30 AM - 6:30 PM) and the AST workday (9:00 AM - 5:00 PM).
- DST Safety: IST or AST may shift during Daylight Saving Time. Always confirm the converted time for your specific date.
- Bombay Stock Exchange (BSE): 09:15-15:30 local time in Mumbai.
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Frequently Asked Questions
What is the time difference between IST and AST?
During standard time, Atlantic Standard Time is 9.5 hours behind Indian Standard Time.
Does India observe Daylight Saving Time (DST)?
India does not observe Daylight Saving Time and has not done so since 1945. IST remains fixed at UTC+5:30 every day of the year, meaning the offset between India and any DST-observing country shifts by one hour twice annually when those countries change their clocks.
Why does IST have a 30-minute offset?
India chose the 82.5° East meridian — which passes through Mirzapur in Uttar Pradesh — as its central reference longitude, as it bisects the subcontinent geographically. That meridian sits exactly 5 hours and 30 minutes ahead of the Prime Meridian in Greenwich, producing the UTC+5:30 offset that has defined IST since 1906.
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.