IST to ACST time conversion
ACST is 4 hours ahead of IST.
ACST is always UTC+9:30. Right now most places that use ACST are on ACDT (UTC+10:30): ACDT is 5 hours ahead of IST.
Time difference with your location
IST is 5 hours 30 minutes ahead of UTC. Compare with your local time →
Choose a date and time
Choose the local time in IST to convert it to ACST on that date.
Skipped clock-change times are unavailable; a repeated time uses its first occurrence.
24-hour conversion chart · IST → ACST
This table converts each hour in IST to ACST on 2026-10-21.
- Working hours
- Outside working hours
- Night hours
| IST | ACST | Shared working hours |
|---|---|---|
| 00:0012:00 AM | 04:004:00 AM | |
| 01:001:00 AM | 05:005:00 AM | |
| 02:002:00 AM | 06:006:00 AM | |
| 03:003:00 AM | 07:007:00 AM | |
| 04:004:00 AM | 08:008:00 AM | |
| 05:005:00 AM | 09:009:00 AM | |
| 06:006:00 AM | 10:0010:00 AM | |
| 07:007:00 AM | 11:0011:00 AM | |
| 08:008:00 AM | 12:0012:00 PM | ✓ |
| 09:009:00 AM | 13:001:00 PM | ✓ |
| 10:0010:00 AM | 14:002:00 PM | ✓ |
| 11:0011:00 AM | 15:003:00 PM | ✓ |
| 12:0012:00 PM | 16:004:00 PM | ✓ |
| 13:001:00 PM | 17:005:00 PM | ✓ |
| 14:002:00 PM | 18:006:00 PM | |
| 15:003:00 PM | 19:007:00 PM | |
| 16:004:00 PM | 20:008:00 PM | |
| 17:005:00 PM | 21:009:00 PM | |
| 18:006:00 PM | 22:0010:00 PM | |
| 19:007:00 PM | 23:0011:00 PM | |
| 20:008:00 PM | 00:0012:00 AM +1 day | |
| 21:009:00 PM | 01:001:00 AM +1 day | |
| 22:0010:00 PM | 02:002:00 AM +1 day | |
| 23:0011:00 PM | 03:003:00 AM +1 day |
Quick conversion examples
These examples use IST (UTC+5:30) and ACST (UTC+9:30); choosing a date applies the local clock changes.
Conversion formula: ACST = IST + 4h · ACDT = IST + 5h.
| IST | ACST |
|---|---|
| 6:00 AM IST | = 10:00 AM ACST |
| 7:00 AM IST | = 11:00 AM ACST |
| 8:00 AM IST | = 12:00 PM ACST |
| 9:00 AM IST | = 1:00 PM ACST |
| 10:00 AM IST | = 2:00 PM ACST |
| 12:00 PM IST | = 4:00 PM ACST |
| 3:00 PM IST | = 7:00 PM ACST |
| 5:00 PM IST | = 9:00 PM ACST |
| 6:00 PM IST | = 10:00 PM ACST |
| 8:00 PM IST | = 12:00 AM ACST (+1 day) |
Overlapping meeting hours
The 08:00–18:00 working day in IST and ACST overlaps for 6 hours on 2026-10-21.
- Shared working hours
- 08:00–14:00 IST · 12:00–18:00 ACST
Clock changes on both sides, 2026–2028
IST and ACST have the following local clock changes in 2026–2028; all times in the table are local to that side.
| Year | IST | ACST |
|---|---|---|
| 2026 | No clock changes; UTC+5:30 all year. | · 03:00 → 02:00 · 02:00 → 03:00 |
| 2027 | No clock changes; UTC+5:30 all year. | · 03:00 → 02:00 · 02:00 → 03:00 |
| 2028 | No clock changes; UTC+5:30 all year. | · 03:00 → 02:00 · 02:00 → 03:00 |
At the start of 2026, ACDT is 5 hours ahead of IST. The difference changes during the following periods.
- From 2026-04-04 22:00 IST until 2026-10-03 22:00 IST, ACST is 4 hours ahead of IST.
- From 2027-04-03 22:00 IST until 2027-10-02 22:00 IST, ACST is 4 hours ahead of IST.
- From 2028-04-01 22:00 IST until 2028-09-30 22:00 IST, ACST is 4 hours ahead of IST.
Frequently asked questions
What time is 9 AM IST in ACST?
9:00 AM IST = 1:00 PM ACST, using UTC+5:30 and UTC+9:30. Choose a date above for the seasonal local time.
Does the time difference between IST and ACST change during the year?
Yes. During 2026–2028: ACST is 4 hours ahead of IST; ACST is 5 hours ahead of IST. The clock-change table gives the dates for both sides.
How do I tell whether it is day or night in ACST?
Read the ACST clock above: this guide counts 06:00–18:00 local time as daytime and the rest as nighttime, without using sunrise and sunset.
What is the best time to call between IST and ACST?
The shared 08:00–18:00 working window is 08:00–14:00 IST / 12:00–18:00 ACST, a total of 6 hours.
What is the time difference between IST and ACST now?
Right now, ACST is 4 hours ahead of IST. Conversion formula: ACST = IST + 4h · ACDT = IST + 5h.