ACST — Australian Central Standard Time
ACST is UTC+09:30, the winter time in Adelaide. In summer, clocks there move to UTC+10:30.
Current time in ACST
00:52:15
Australian Central Standard Time · UTC+09:30
About ACST
South Australia switches to ACDT (UTC+10:30) in summer; the Northern Territory stays on ACST.
Working with ACST
No other zone in this directory uses UTC+09:30. No zone in this directory sits exactly one hour either side of ACST; the nearest listed offsets belong to JST (UTC+09:00) and KST (UTC+09:00).
Clock changes in ACST
ACST is a southern-hemisphere zone, so its summer time runs across the new year: clocks go forward in October and back in April.
| Date | Change | New offset |
|---|---|---|
| April 4, 2027 | Clocks go back one hour on Apr 4, 2027 at 03:00, moving from UTC+10:30 to UTC+09:30. | UTC+09:30 |
| October 3, 2027 | Clocks go forward one hour on Oct 3, 2027 at 02:00, moving from UTC+09:30 to UTC+10:30. | UTC+10:30 |
Clock history of Australia/Adelaide
| Period | Clocks set to | Seasonal changes |
|---|---|---|
| since 1900 | UTC+09:30 | 60 years with a change, 1917–2026 |
Who keeps UTC+09:30
No city in this directory keeps UTC+09:30 all year. Part of the year: Adelaide from April 4, 2027 to October 3, 2027.
Countries and territories that keep UTC+09:30 all year, from every entry in the tz database: parts of Australia. For part of the year: parts of Australia.
| City | Longitude | Solar noon on ACST |
|---|---|---|
| Adelaide | 138.60°E | 12:16 |
Where ACST stands today
ACST is not in force in Australia/Adelaide at the moment: clocks there are on UTC+10:30 until April 4, 2027, 152 days from the day this page was generated, when they return to ACST. A time written as ACST still means UTC+09:30 on any date, which is why naming the place is safer than naming the abbreviation.
Australia/Adelaide is on summer time at the moment, so local clocks there are not showing ACST itself.
A working day on ACST
| Place | ACST’s 09:00–17:00 there | Over the next 12 months |
|---|---|---|
| UTC | 23:30–07:30 (previous day) | — |
| New York | 18:30–02:30 (previous day) / 19:30–03:30 (previous day) | none all year |
| London | 23:30–07:30 (previous day) / 00:30–08:30 | none all year |
| Tokyo | 08:30–16:30 | always 7 h 30 min |
At 09:00 on a Monday on ACST time, São Paulo, Lima, Mexico City, New York, Bogotá, Rio de Janeiro and 27 more are still on Sunday. For part of the year, so are London, Dublin, Manchester, Lisbon and Edinburgh. At 17:00 on a Friday on ACST time, no city in this directory has reached Saturday yet.
For the working hours Adelaide shares with New York, London and Tokyo, and for its sunrise and sunset through the year, see the Adelaide page.
How ACST compares with other zones
Right now ACST runs ahead of UTC, New York, London, Berlin, Dubai, Kolkata, Singapore, Tokyo and Los Angeles and behind Sydney.
| Zone | UTC offset | Difference from ACST | Over the next 12 months |
|---|---|---|---|
| UTC | UTC+00:00 | 9h 30m ahead | all year |
| New York | UTC-05:00 | 14h 30m ahead | 14h 30m ahead / 13h 30m ahead |
| London | UTC+00:00 | 9h 30m ahead | 9h 30m ahead / 8h 30m ahead |
| Berlin | UTC+01:00 | 8h 30m ahead | 8h 30m ahead / 7h 30m ahead |
| Dubai | UTC+04:00 | 5h 30m ahead | all year |
| Kolkata | UTC+05:30 | 4h ahead | all year |
| Singapore | UTC+08:00 | 1h 30m ahead | all year |
| Tokyo | UTC+09:00 | 0h 30m ahead | all year |
| Sydney | UTC+11:00 | 1h 30m behind | 0h 30m behind / 1h 30m behind |
| Los Angeles | UTC-08:00 | 17h 30m ahead | 17h 30m ahead / 16h 30m ahead |
Cities using ACST
- Adelaide
- Darwin
Convert ACST to another zone
Related time zones
Time zone rules: IANA tz database release 2026c, applied when this page was generated on 2026-11-02.
Frequently asked questions
What is ACST?
Australian Central Standard Time, ACST, is UTC+09:30. South Australia switches to ACDT (UTC+10:30) in summer; the Northern Territory stays on ACST.
What is the IANA identifier for ACST?
Australia/Adelaide, named after Adelaide. It has moved between UTC+09:30 and UTC+10:30 on the same yearly pattern since 2008.
Does ACST change for daylight saving?
ACST itself never changes: it always means UTC+09:30. Australia/Adelaide moves between UTC+09:30 in winter and UTC+10:30 in summer, so a time labelled ACST only matches the local clock there for part of the year.
What time is it on ACST when it is 09:00 in London?
18:30 until March 28, 2027 and from October 31, 2027; 17:30 from March 28, 2027 to October 31, 2027.