ACST — Australian Central Standard Time
ACST is Australian Central Standard Time, 9 hours 30 minutes ahead of UTC. It is a fixed offset: unlike a time zone, it does not change with the season — the zones that use it switch to a different abbreviation instead.
Current time in ACST
17:16
Sunday, 2 August 2026
ACST = UTC+9:30 · 9 hours 30 minutes ahead of UTC
Shown for 2 Aug 2026 07:46 UTC. The clock goes live as soon as scripts load.
UTC offset
UTC+9:30
Type
Standard time
Seasonal counterpart
ACDT
The letters the same zones use for the other half of the year
Meanings
1
Unambiguous
Is ACST in force right now?
A zone only carries this abbreviation for part of the year. This is which of them were on it at 2 Aug 2026 07:46 UTC; the list is re-derived against your own clock when scripts load.
On ACST now
- Australia/Adelaide — Adelaide
- Australia/Darwin — Darwin
Using a different abbreviation
- Every zone listed here was on ACST.
ACST alternates with ACDT across the year.
Writing “ACST” for a date in the other half of the year is the most common time zone mistake in meeting invitations.
Convert ACST to other time zones
City clocks reflect whatever their zone is doing; where a city observes daylight saving time, its difference from ACST changes twice a year. Use the time zone converter for a specific date.
Time zones and cities that use ACST
Why ACST is not an identifier
ACST is shorthand, not a standard. There is no registry of time zone abbreviations, no authority that assigns them, and nothing preventing two regions from adopting the same three letters — which is what makes codes like IST and CST unusable without context.
For anything a machine will read — a calendar invitation, a database column, an API response — use the IANA identifier of the zone (Australia/Adelaide, for example) or an explicit UTC offset alongside the date. The identifier survives a change in the law; ACST and its 9 hours 30 minutes offset do not.
Frequently asked questions
What does ACST stand for?
ACST stands for Australian Central Standard Time. It is 9 hours 30 minutes ahead of UTC, written UTC+9:30.
What is ACST in UTC?
ACST is UTC+9:30. To convert an ACST time to UTC, subtract 9 hours 30 minutes.
What is the difference between ACST and ACDT?
ACST is the standard-time form; ACDT is what those same zones use during daylight saving time, one hour ahead. A summer date written "ACST" is usually a mistake for ACDT.
Which time zone should I use instead of ACST?
Use an IANA identifier — Australia/Adelaide and Australia/Darwin for Australian Central Standard Time — or state the UTC offset with the date. Abbreviations are not identifiers: they are not unique, they are not registered anywhere, and half of them change with the season. Calendar software resolves this automatically when you pick a city rather than typing letters.