AST to IST Converter
Understanding AST and IST Time Zones
Atlantic Standard Time (AST)
Atlantic Standard Time is observed in undefined and uses the offset UTC-4. Major cities in this time zone include Halifax, San Juan. This time zone serves a significant global region with important economic and cultural hubs.
India Standard Time (IST)
India Standard Time operates at UTC+5.5, covering undefined. Key cities include Mumbai, Delhi, Bangalore. The 9.5-hour forward offset from AST means that when professionals in Halifax start their workday at 9:00 AM, it is already 6:30 PM in Mumbai.
AST is also commonly referred to as Atlantic Time, Puerto Rico time. IST is also known as India time, Indian time, Mumbai time, Delhi time. So if you are searching for Atlantic Time to India time, this is the same conversion as AST to IST.
Complete AST to IST Conversion Table
The table below shows every two-hour increment converted from Atlantic Standard Time to India Standard Time. Business hours (9 AM – 5 PM) are highlighted for easy scheduling reference.
| AST (Atlantic Standard Time) | IST (India Standard Time) |
|---|---|
| 12:00 AM (00:00) | 9:30 AM (09:30) |
| 2:00 AM (02:00) | 11:30 AM (11:30) |
| 4:00 AM (04:00) | 1:30 PM (13:30) |
| 6:00 AM (06:00) | 3:30 PM (15:30) |
| 8:00 AM (08:00) | 5:30 PM (17:30) |
| 10:00 AM (10:00) | 7:30 PM (19:30) |
| 12:00 PM (12:00) | 9:30 PM (21:30) |
| 2:00 PM (14:00) | 11:30 PM (23:30) |
| 4:00 PM (16:00) | 1:30 AM (01:30) (next day) |
| 6:00 PM (18:00) | 3:30 AM (03:30) (next day) |
| 8:00 PM (20:00) | 5:30 AM (05:30) (next day) |
| 10:00 PM (22:00) | 7:30 AM (07:30) (next day) |
Times shown in 12-hour and 24-hour format. Last updated 2026-03-09.
Scheduling Between AST and IST
Freelancers and contractors working across AST and IST should clearly state their invoicing time zone. A 9.5-hour difference means an "end of business day" deliverable could mean very different things to each party.
The large 9.5-hour gap between AST and IST means that finding overlapping working hours requires compromise from at least one side. Consider adopting asynchronous workflows — recorded video updates, shared documents, and time-zone-aware project management tools — to supplement the limited real-time overlap.
Travel Between Halifax and Mumbai
For layover planning between undefined and undefined destinations, connecting flights often involve intermediate time zones. Use our converter to verify each leg independently to avoid missed connections.
Medical experts recommend allowing approximately one day of adjustment per hour of time difference. For the 9.5-hour shift between AST and IST, plan for roughly one week of gradual adjustment for optimal performance.
Daylight Saving Time Considerations
Some regions within a time zone do not observe DST. Arizona (MST) and Hawaii (HST) stay on standard time year-round, which can create unexpected offsets with neighboring states during summer months.
For the AST to IST conversion specifically: AST (UTC-4) and IST (UTC+5.5) neither observes DST, so the 9.5-hour offset remains constant throughout the year. This makes scheduling reliable and predictable.
Related Time Zone Conversions
References & Resources
Frequently Asked Questions
AST (Atlantic Standard Time) is 9.5 hours behind IST (India Standard Time). AST is UTC-4 and IST is UTC+5.5.
When it is 12:00 PM (noon) in AST, it is 9:30 PM in IST.
The best overlap for business hours is approximately 6:00 PM to 2:00 AM IST, which corresponds to 9:00 AM to 5:00 PM in AST. Given the large gap, consider alternating between early and late meeting times.
Some regions within a time zone do not observe DST. Arizona (MST) and Hawaii (HST) stay on standard time year-round, which can create unexpected offsets with neighboring states during summer months.