IST to ACST: IST is 4 hours behind ACST
India Standard Time is 4 hours behind Australian Central Time right now. It is 7:47 am IST in India and 11:47 am ACST in Australian Central.
Convert a specific time from IST to ACST
Pick any time and date to convert it both ways. The conversion runs in your browser against the real zone rules, so a date inside a daylight saving period gets that period's offset rather than today's.
What is the time difference between IST and ACST?
Australian Central Time is 4 hours ahead of India Standard Time. To go from IST to ACST you add 4 hours. That gap is not fixed. Across 2026 the distance between these two zones takes 2 different values, from 4 hours to 5 hours, because Australian Central moves its clocks and India does not. This page recomputes it rather than assuming.
IST to ACST conversion table
Every hour of Friday, September 25, 2026 in India, with the matching reading in Australian Central. 4 of the 24 hours land on a different calendar date in Australian Central, which is the part people get wrong when they schedule across this pair.
| IST | IST 24h | ACST | ACST 24h | Date |
|---|---|---|---|---|
| 12:00 am | 00:00 | 4:00 am | 04:00 | same day |
| 1:00 am | 01:00 | 5:00 am | 05:00 | same day |
| 2:00 am | 02:00 | 6:00 am | 06:00 | same day |
| 3:00 am | 03:00 | 7:00 am | 07:00 | same day |
| 4:00 am | 04:00 | 8:00 am | 08:00 | same day |
| 5:00 am | 05:00 | 9:00 am | 09:00 | same day |
| 6:00 am | 06:00 | 10:00 am | 10:00 | same day |
| 7:00 am | 07:00 | 11:00 am | 11:00 | same day |
| 8:00 am | 08:00 | 12:00 pm | 12:00 | same day |
| 9:00 am | 09:00 | 1:00 pm | 13:00 | same day |
| 10:00 am | 10:00 | 2:00 pm | 14:00 | same day |
| 11:00 am | 11:00 | 3:00 pm | 15:00 | same day |
| 12:00 pm | 12:00 | 4:00 pm | 16:00 | same day |
| 1:00 pm | 13:00 | 5:00 pm | 17:00 | same day |
| 2:00 pm | 14:00 | 6:00 pm | 18:00 | same day |
| 3:00 pm | 15:00 | 7:00 pm | 19:00 | same day |
| 4:00 pm | 16:00 | 8:00 pm | 20:00 | same day |
| 5:00 pm | 17:00 | 9:00 pm | 21:00 | same day |
| 6:00 pm | 18:00 | 10:00 pm | 22:00 | same day |
| 7:00 pm | 19:00 | 11:00 pm | 23:00 | same day |
| 8:00 pm | 20:00 | 12:00 am | 00:00 | the next day |
| 9:00 pm | 21:00 | 1:00 am | 01:00 | the next day |
| 10:00 pm | 22:00 | 2:00 am | 02:00 | the next day |
| 11:00 pm | 23:00 | 3:00 am | 03:00 | the next day |
What are the best hours to schedule a call between IST and ACST?
4 hours of the standard 9:00 am to 5:00 pm working day line up in both zones, from 9:00 am IST to 1:00 pm IST. In Australian Central that window reads 1:00 pm to 5:00 pm. Outside it, one side is either not yet at their desk or already gone.
| IST | ACST | Working hours | Note |
|---|---|---|---|
| 9:00 am | 1:00 pm | both sides | mid morning in India, afternoon in Australian Central |
| 10:00 am | 2:00 pm | both sides | mid morning in India, afternoon in Australian Central |
| 11:00 am | 3:00 pm | both sides | mid morning in India, afternoon in Australian Central |
| 12:00 pm | 4:00 pm | both sides | noon in India, afternoon in Australian Central |
Does daylight saving change IST to ACST?
India Standard Time does not move its clocks at all, so its UTC+5:30 offset holds every day of the year.
Australian Central Time is currently on ACST and changes next on Sunday, October 4, 2026, when the clock jumps forward from 1:59 am to 3:00 am and the offset moves from UTC+9:30 to UTC+10:30.
Because the two sides do not move together, the answer to this conversion changes during the year. For part of the year the gap is 4 hours and for the rest it is 5 hours. The table above is built for today, not for an average day.
Is IST ahead of or behind ACST?
IST is behind ACST by 4 hours: when it is 12:00 pm in India, it is 4:00 pm in Australian Central. One wrinkle worth knowing: ACST and ACDT are two names for the same zone, not two zones. Australian Central Time reads ACST in winter and ACDT in summer. When somebody types "ist to acst" they nearly always mean the zone rather than the literal winter offset, so this page resolves IST to Asia/Kolkata and ACST to Australia/Adelaide and applies whichever offset is genuinely in force on the day.
India Standard Time covers the whole of India on a single half hour offset. Australian Central Time covers Adelaide and South Australia, on a half hour offset that also shifts for summer. The identifiers behind them are Asia/Kolkata and Australia/Adelaide, which is what any calendar or scheduling system should be storing rather than a fixed number of hours.
Questions
- What is IST in ACST?
- IST is 4 hours behind ACST. 9:00 am IST is 1:00 pm ACST.
- How many hours ahead is ACST of IST?
- ACST is 4 hours ahead of IST. That varies across the year, between 4 hours and 5 hours.
- What time is it in Australian Central right now?
- 11:47 am ACST on Friday, September 25, 2026.
- When can India and Australian Central meet during working hours?
- Between 9:00 am and 1:00 pm IST, which is 1:00 pm to 5:00 pm ACST.
- Does this account for daylight saving?
- Yes. Every reading is computed from the IANA database for the actual date, so IST and ACST are the abbreviations genuinely in force today rather than a fixed assumption.
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