AST to IST Time Converter
IST is 8 hours and 30 minutes ahead of AST. Atlantic Canada and the Caribbean are currently on ADT (UTC-3:00), and IST is UTC+5:30.
Best Time to Call Between AST and IST
Standard 9-to-5 hours in these two zones never overlap, so someone has to take the call outside their working day. The most workable window is 7:00 AM to 2:00 PM AST, which is 3:30 PM to 10:30 PM IST.
both at work AST only IST only neither — hours along the strip are AST.
Common Times Converted
AST on the left, IST on the right.
AST to IST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| AST | IST | Working hours |
|---|---|---|
| 12:00 AM | 8:30 AM | — |
| 1:00 AM | 9:30 AM | IST only |
| 2:00 AM | 10:30 AM | IST only |
| 3:00 AM | 11:30 AM | IST only |
| 4:00 AM | 12:30 PM | IST only |
| 5:00 AM | 1:30 PM | IST only |
| 6:00 AM | 2:30 PM | IST only |
| 7:00 AM | 3:30 PM | IST only |
| 8:00 AM | 4:30 PM | IST only |
| 9:00 AM | 5:30 PM | AST only |
| 10:00 AM | 6:30 PM | AST only |
| 11:00 AM | 7:30 PM | AST only |
| 12:00 PM | 8:30 PM | AST only |
| 1:00 PM | 9:30 PM | AST only |
| 2:00 PM | 10:30 PM | AST only |
| 3:00 PM | 11:30 PM | AST only |
| 4:00 PM | 12:30 AM next day | AST only |
| 5:00 PM | 1:30 AM next day | — |
| 6:00 PM | 2:30 AM next day | — |
| 7:00 PM | 3:30 AM next day | — |
| 8:00 PM | 4:30 AM next day | — |
| 9:00 PM | 5:30 AM next day | — |
| 10:00 PM | 6:30 AM next day | — |
| 11:00 PM | 7:30 AM next day | — |
What AST and IST Actually Are
AST — Atlantic Standard Time
Halifax, San Juan, Santo Domingo, Bermuda. Standing at UTC-4:00 as written, and the region does change its clocks, so its live offset moves by an hour twice a year. The next change is on Sunday, November 1, 2026, to AST. AST also stands for Arabia Standard Time (UTC+3), used in Saudi Arabia, Iraq and Kuwait.
Atlantic Standard Time is the only North American zone whose name is more commonly associated, worldwide, with a completely different zone — Arabia Standard Time.
IST — India Standard Time
Mumbai, Delhi, Bengaluru, Chennai, Kolkata, Hyderabad — and Colombo. Standing at UTC+5:30 as written, and the region does not change its clocks, so that offset holds all year. IST also stands for Irish Standard Time (UTC+1) and Israel Standard Time (UTC+2). This page covers the Indian one, which is by far the most searched.
India runs a single time zone across a country wide enough for two, which is why sunrise in the north-east can come nearly two hours before Mumbai's. Proposals for a second zone resurface regularly and have never been adopted.
What This Means in Practice
Expect times on the half hour
IST sits on a 30-minute offset rather than a whole hour, so a round number on one side is never a round number on the other. A 9:00 meeting becomes 30 minutes past the hour, which is exactly the detail calendar invitations get wrong when someone converts in their head.
The date changes mid-working-day
For 1 of the eight hours in a normal AST working day, the equivalent IST time falls on a different calendar date. Anything scheduled in that stretch needs the date checked as well as the time, or a Tuesday call quietly becomes a Wednesday one at the other end.
This gap is not fixed
AST changes its clocks and IST does not, so the difference between them moves by an hour twice a year. A recurring meeting set now will drift for one side from Sunday, November 1, 2026 unless someone resets it.
Major Cities in Each Zone
Cities on AST
Cities on IST
Frequently Asked Questions
What is the time difference between AST and IST?
IST is 8 hours and 30 minutes ahead of AST. That is the live figure. Taken strictly as written, the gap between AST and IST is 9 hours and 30 minutes — the two differ because at least one of these regions is currently on daylight saving.
What is 9:00 AM AST in IST?
9:00 AM AST is 5:30 PM IST.
What are the best hours to schedule a call between AST and IST?
Standard business hours in these two zones do not overlap at all, so one side has to work outside the 9-to-5. The most workable window is 7:00 AM to 2:00 PM AST, which is 3:30 PM to 10:30 PM IST.
Does the difference between AST and IST change during the year?
Yes. AST observes daylight saving and IST does not, so the gap shifts by an hour at least twice a year. The next clock change is on Sunday, November 1, 2026.
Does AST always mean Atlantic Standard Time?
AST also stands for Arabia Standard Time (UTC+3), used in Saudi Arabia, Iraq and Kuwait.
Does IST always mean India Standard Time?
IST also stands for Irish Standard Time (UTC+1) and Israel Standard Time (UTC+2). This page covers the Indian one, which is by far the most searched.