IST to ACST Time Converter

When it is 9:00 AM IST, it is 1:00 PM ACST. Australian Central Standard Time (ACST, UTC+9:30) is 4 hours ahead of India Standard Time (IST, UTC+5:30). Your working-hours overlap window is 9:00 AM–1:00 PM IST (1:00 PM–5:00 PM ACST).

IST to ACST Conversion Table

Major Cities Using IST and ACST

India Standard Time (IST): Mumbai, Delhi, Bangalore, Chennai, Kolkata, Colombo.

Australian Central Standard Time (ACST): Adelaide, Darwin.

How many hours between IST and ACST?

IST is UTC+5:30 and ACST is UTC+9:30, a difference of 4 hours. ACST is ahead of IST. This difference can shift by an hour in either direction during Daylight Saving Time transitions — if one zone observes DST and the other doesn't, the offset narrows or widens for part of the year.

Business Hours Overlap: IST ↔ ACST

Assuming a 9:00 AM – 5:00 PM workday on each side, your working-hours overlap window is 9:00 am–1:00 pm ist (1:00 pm–5:00 pm acst). To visualize this instantly for any pair of cities, use the visual meeting planner or the timezone overlap finder — both highlight the green overlap window on a live timeline.

Does IST observe Daylight Saving Time?

India Standard Time (IST) is based on the Asia/Kolkata IANA timezone. DST observance depends on the jurisdiction — for example, most of the continental US switches between standard and daylight time, while India, Japan, and most of Southeast Asia do not observe DST at all. WorldClock.lol uses the authoritative IANA timezone database, so every conversion automatically accounts for the correct DST rules on the date you're converting.

When is 9 AM IST in ACST?

When it is 9:00 AM in India Standard Time (IST, UTC+5:30), it is 1:00 PM in Australian Central Standard Time (ACST). For other times of day, scan the conversion table above or drop into the interactive converter to pick an exact minute. The converter handles both standard and daylight variants correctly.

How to Use This IST to ACST Converter

1. Type or drag any time in the IST input above — the ACST equivalent updates instantly.
2. Check the day indicator. When the converted time crosses midnight, the tool shows +1 day or −1 day so you don't book a meeting on the wrong date.
3. Copy the shareable URL to send the specific conversion to a colleague — the link preserves your exact selection.
4. Switch directions by swapping the input zones, or open ACST to IST for the reverse.

Related IST Converters

• IST to EST
• IST to PST
• IST to GMT
• IST to UTC
• IST to JST
• IST to CET

Related ACST Converters

• EST to ACST
• PST to ACST
• GMT to ACST
• UTC to ACST
• JST to ACST
• CET to ACST

More Time Tools

• All Time Zone Converters — browse every supported pair
• About IST (India Standard Time) — current time, cities, DST rules
• About ACST (Australian Central Standard Time) — current time, cities, DST rules
• Meeting Planner — find the best time for a multi-city meeting
• Best Time to Call — optimal calling windows between any two cities
• UTC Time Now — the reference point for every conversion
• DST Schedule 2026 — every daylight-saving transition this year