What is the time difference between IRST and ACST?

Australian Central Standard Time (ACST) is 6 hours ahead of Iran Standard Time (IRST). IRST uses a UTC offset of UTC+3:30, while ACST uses UTC+9:30. For example, when it's 9:00 AM in IRST, it's 3:00 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 IRST to ACST?

To convert IRST to ACST, add 6 hours to the IRST time. For example, 9:00 AM IRST is 3:00 PM ACST, and 5:00 PM IRST is 11:00 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 IRST?

When it's 12:00 PM (noon) in IRST, it's 6:00 PM in ACST. This is because ACST is 6 hours ahead of IRST. Similarly, when it's 6:00 PM in IRST, it's 12:00 AM 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 IRST?

ACST is 6 hours ahead of IRST. This means when it's 9:00 AM in IRST, it's 3:00 PM in ACST, and when it's midnight in IRST, it's 6:00 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 IRST?

ACST is ahead of IRST by 6 hours. Clocks in ACST show a later time than IRST, meaning the day starts earlier in ACST relative to IRST. For example, when it's morning in IRST, it's already afternoon or evening in ACST. This gap may change by one hour during DST transitions.

Does IRST observe daylight saving time?

No, Iran Standard Time does not observe daylight saving time. The UTC offset of UTC+3:30 remains the same year-round, which simplifies time conversions. Regions using IRST 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 IRST to ACST conversions.

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

The best time for a call between IRST 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 3:00 AM and 11:00 AM your IRST time. Avoid calling too early or late, as the 6 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 IRST 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 IRST and ACST ever have the same time?

No, IRST and ACST never show the same time because their base UTC offsets are different. However, because ACST observes daylight saving time and IRST 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.

IRST to ACST Converter

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

Timezone Details

Tehran

5:03 AM

Tuesday, June 9, 2026

Tehran (UTC+03:30)

Australian Central Standard Time

11:03 AM

Tuesday, June 9, 2026

ACST (UTC+09:30)

Difference: +6 hours

ACST DST: Yes (ACDT)

24-Hour Overview

Tehran — 24-hour overview

12a12a

3a3a

6a6a

9a9a

10a

11a

12p12p

3p3p

6p6p

9p9p

10p

11p

NightMorningBusinessEvening

ACST — 24-hour overview

6a6a

9a9a

10a

11a

12p12p

3p3p

6p6p

9p9p

10p

11p

12a12a

3a3a

NightMorningBusinessEvening

Frequently Asked Questions

Related Conversions

ACST to IRST

Cities in These Timezones

IRST Cities

Tehran

ACST Cities

Adelaide

More Tools

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

Learn More

How Time Zones Work Understanding DST Timezone Abbreviations

External Resources

Australian Central Standard Time on Wikipedia IANA Time Zone Database