AST to IST Converter
Convert time between Atlantic Standard Time (AST) and India Standard Time (IST)
Atlantic Standard Time (AST)
India Standard Time (IST)
Time Difference
India Standard Time (IST) is 0 hours ahead of Atlantic Standard Time (AST)
Select Date
Select Time
Quick Reference
| AST | IST |
|---|---|
| 23:00 | 07:30 |
| 01:00 | 09:30 |
| 03:00 | 11:30 |
| 05:00 | 13:30 |
| 07:00 | 15:30 |
| 09:00 | 17:30 |
| 11:00 | 19:30 |
| 13:00 | 21:30 |
| 15:00 | 23:30 |
| 17:00 | 01:30 |
| 19:00 | 03:30 |
| 21:00 | 05:30 |
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 AST to IST Time Conversion
Converting time between Atlantic Standard Time (AST) and India Standard Time (IST) is essential for coordination between Atlantic Canada and India. AST is UTC-4, while IST is UTC+5:30, making IST 9.5 hours ahead of AST.
This conversion is particularly useful for businesses operating across Atlantic Canada and Indian markets, technology teams, and individuals maintaining personal connections. India does not observe daylight saving time, so IST remains constant while Atlantic Canada transitions between AST and ADT.
Common Use Cases for AST to IST Conversion
Business & Work
- Scheduling meetings between Atlantic Canada and Indian business teams
- Coordinating IT support and software development projects across time zones
- Planning conference calls for companies with offices in both regions
Personal & Travel
- Keeping in contact with family and friends in India from Atlantic Canada
- Planning international travel between Atlantic Canada and India
- Scheduling virtual events and online activities across both time zones
Time Zone Information
Atlantic Standard Time (AST)
- UTC Offset: UTC-4 (UTC-3 during ADT)
- IANA Timezone: America/Halifax
- Daylight Saving: Second Sunday in March to First Sunday in November
- Major Cities: Halifax, Moncton, Saint John, Fredericton, Charlottetown
- Coverage: Atlantic Canada (Nova Scotia, New Brunswick, PEI, Labrador)
India Standard Time (IST)
- UTC Offset: UTC+5:30 (no daylight saving)
- IANA Timezone: Asia/Kolkata
- Daylight Saving: No daylight saving time
- Major Cities: New Delhi, Mumbai, Bangalore, Hyderabad, Chennai, Kolkata
- Coverage: Entire India
Quick Reference: AST to IST
Remember: IST is always 9.5 hours ahead of AST (8.5 hours when ADT is active)
Frequently Asked Questions
What is the time difference between AST and IST?
Atlantic Standard Time (AST) is UTC-4, while India Standard Time (IST) is UTC+5:30. IST is 9.5 hours ahead of AST. When it's 9:00 AM in Halifax, it's 6:30 PM in New Delhi.
When does this AST to IST conversion apply?
AST applies in Atlantic Canada from the first Sunday in November to the second Sunday in March. During the rest of the year, the region uses ADT (UTC-3), making IST only 8.5 hours ahead.
Does India observe daylight saving time?
No, India does not observe daylight saving time. IST is fixed at UTC+5:30 throughout the year. The offset change only comes from Atlantic Canada switching between AST and ADT.
What are the best times for AST-IST business calls?
A morning call at 9:00 AM AST is 6:30 PM IST — good for a late India business-hours window. A 10:00 AM AST call lands at 7:30 PM IST, which suits both sides well.
Which regions use IST?
India Standard Time covers all of India including the Andaman and Nicobar Islands and Lakshadweep. It is a single time zone for the entire country, unique for its 30-minute offset.
Which regions use AST?
Atlantic Standard Time is used in Atlantic Canada (Nova Scotia, New Brunswick, Prince Edward Island, Labrador) and in parts of the Caribbean including Puerto Rico and the US Virgin Islands year-round.
Pro Tips
- • IST is 9.5 hours ahead of AST — add 9 hours and 30 minutes to AST to get IST.
- • Atlantic Canada uses ADT (UTC-3) in summer, reducing the gap to 8.5 hours.
- • India never changes clocks, so IST stays at UTC+5:30 all year.
- • A 9:00–11:00 AM AST window maps to 6:30–8:30 PM IST — solid overlap for end-of-day India meetings.
- • Puerto Rico and the US Virgin Islands use AST year-round (no daylight saving transition).
- • Double-check the offset if scheduling near the Atlantic Canada DST changeover dates in March or November.