What is the time difference between IST and ACST?

Australian Central Standard Time (ACST) is 4 hours ahead of India Standard Time (IST). IST uses a UTC offset of UTC+5:30, while ACST uses UTC+9:30. For example, when it's 9:00 AM in IST, it's 1:00 PM in ACST. Note that this difference may shift by one hour during daylight saving time transitions if ACST observes DST. Use the conversion table above to see the exact time for each hour of the day.

How do I convert IST to ACST?

To convert IST to ACST, add 4 hours to the IST time. For example, 9:00 AM IST is 1:00 PM ACST, and 5:00 PM IST is 9:00 PM ACST. Keep in mind that during daylight saving time transitions, the offset between these timezones may temporarily change by one hour. You can also use the interactive converter above for quick, accurate results.

What time is it in ACST when it's noon in IST?

When it's 12:00 PM (noon) in IST, it's 4:00 PM in ACST. This is because ACST is 4 hours ahead of IST. Similarly, when it's 6:00 PM in IST, it's 10:00 PM in ACST. During daylight saving time transitions, these times may shift by one hour, so always verify the current offset. The color-coded conversion table above shows every hour mapped between both timezones.

How many hours ahead is ACST from IST?

ACST is 4 hours ahead of IST. This means when it's 9:00 AM in IST, it's 1:00 PM in ACST, and when it's midnight in IST, it's 4:00 AM in ACST. The exact difference can vary by one hour during daylight saving time transitions. The conversion table above provides a complete hour-by-hour mapping.

Is ACST ahead or behind IST?

ACST is ahead of IST by 4 hours. Clocks in ACST show a later time than IST, meaning the day starts earlier in ACST relative to IST. For example, when it's morning in IST, it's later in the morning in ACST. This gap may change by one hour during DST transitions.

Does IST observe daylight saving time?

No, India Standard Time does not observe daylight saving time. The UTC offset of UTC+5:30 remains the same year-round, making time conversions from IST more predictable. Countries and regions in this timezone keep their clocks unchanged regardless of the season.

Does ACST observe daylight saving time?

Yes, Australian Central Standard Time observes daylight saving time. During DST, the abbreviation changes to ACDT and clocks move forward by one hour, typically in spring. Clocks then fall back in autumn, returning to standard ACST time. This means the UTC offset for ACST shifts between two values depending on the season. Check our DST change calendar for exact transition dates that may affect your IST to ACST conversions.

What is the best time to call from IST to ACST?

The best time for a call between IST and ACST is during overlapping business hours (9 AM – 5 PM) in both timezones. To reach someone in ACST during their work day, call between 5:00 AM and 1:00 PM your IST time. Avoid calling too early or late, as the 4 hours difference means your evening could be their late night. Check the color-coded conversion table above — green hours indicate business hours in both zones, making it easy to find the ideal time.

When does daylight saving time change in ACST?

Daylight saving time transitions vary by year and region. Australian Central Standard Time observes DST, which typically shifts clocks forward by one hour in spring ("spring forward") and back in fall ("fall back"). During these transition periods, the time difference between IST and ACST may temporarily change by one hour, which can cause confusion for scheduled meetings or calls. It's important to double-check your conversions around transition dates, especially if the two timezones switch on different dates. Check our DST change calendar for exact transition dates in the current year.

Do IST and ACST ever have the same time?

No, IST and ACST never show the same time because their base UTC offsets are different. However, because ACST observes daylight saving time and IST does not, the time difference between them changes by one hour during DST transitions. This means the gap narrows or widens depending on the season, but the two clocks never align. Always verify the current offset around DST transition dates to avoid scheduling errors.

IST to ACST Converter

Convert India Standard Time to Australian Central Standard Time. See the hour-by-hour conversion table below.

Timezone Details

India Standard Time

6:49 AM

Tuesday, June 9, 2026

IST (UTC+05:30)

Australian Central Standard Time

10:49 AM

Tuesday, June 9, 2026

ACST (UTC+09:30)

Difference: +4 hours

IST DST: No

ACST DST: Yes (ACDT)

24-Hour Overview

IST — 24-hour overview

12a12a

3a3a

6a6a

9a9a

10a

11a

12p12p

3p3p

6p6p

9p9p

10p

11p

NightMorningBusinessEvening

ACST — 24-hour overview

4a4a

7a7a

10a10a

11a

12p

1p1p

4p4p

7p7p

10p10p

11p

12a

1a1a

NightMorningBusinessEvening

Frequently Asked Questions

Related Conversions

ACST to IST EST to IST IST to EST PST to IST IST to PST GMT to IST IST to GMT IST to JST JST to IST

Cities in These Timezones

IST Cities

Delhi Mumbai Kolkata Bangalore Chennai

ACST Cities

Adelaide

More Tools

Compare IST & ACST Plan a Meeting (IST & ACST)See on Map

Learn More

How Time Zones Work Understanding DST Timezone Abbreviations

External Resources

India Standard Time on Wikipedia Australian Central Standard Time on Wikipedia IANA Time Zone Database