ACST to GST
-5h 30mACST
ACSTSOURCEGST
GSTGreen rows indicate typical business hours (9 AM - 5 PM)
ACST and GST on the World Map
The map below highlights the ACST (Australian Central Standard Time) and GST (Gulf Standard Time) timezone regions across the globe.
ACST – Australian Central Standard Time
UTC+09:30Australian Central Standard Time (ACST, UTC+09:30) covers South Australia and the Northern Territory, on a half-hour offset.
- •ACST uses a half-hour offset: UTC+09:30.
- •South Australia moves to ACDT (UTC+10:30) in summer; the Northern Territory does not.
- •Adelaide and Darwin are 30 minutes apart during daylight saving, level in winter.
- •Adelaide is one of the few major cities on a 30-minute offset.
GST – Gulf Standard Time
UTC+04:00Gulf Standard Time (GST) is used in the UAE, Oman, and other Gulf states, 4 hours ahead of UTC.
- •Dubai uses GST year-round with no daylight saving time.
- •GST is 9 hours ahead of EST and 4 hours ahead of GMT.
- •The Dubai Financial Market (DFM) operates on GST.
Everything You Need to Know About ACST and GST Time
ACST runs on Australian Central Standard Time (ACST) at UTC+09:30. GST runs on Gulf Standard Time (GST) at UTC+04:00. That puts ACST 5 hours 30 minutes behind GST — a difference of -5h 30m at the current offsets.
In practice, when it is 9:00 AM in ACST it is 3:30 AM in GST. Midnight in ACST is 6:30 PM in GST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
ACST to GST time conversion table
| ACST (ACST) | GST (GST) | Day |
|---|---|---|
| 12:00 AM | 6:30 PM | previous day |
| 6:00 AM | 12:30 AM | same day |
| 7:00 AM | 1:30 AM | same day |
| 8:00 AM | 2:30 AM | same day |
| 9:00 AM | 3:30 AM | same day |
| 12:00 PM | 6:30 AM | same day |
| 3:00 PM | 9:30 AM | same day |
| 5:00 PM | 11:30 AM | same day |
| 6:00 PM | 12:30 PM | same day |
| 9:00 PM | 3:30 PM | same day |
Why people convert ACST to GST time
- Scheduling a call from ACST to GST: a 10:00 AM start in ACST lands at 4:30 AM in GST, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both ACST and GST are inside the 9-to-5 working day between 2:30 PM and 5:00 PM ACST time (9:00 AM–11:30 AM GST). That is roughly 2 hours 30 minutes of usable overlap.
- Keeping family and friends in sync: knowing that 8:00 PM in ACST is 2:30 PM in GST makes it easy to avoid calling at 3 AM.
- Always state the zone abbreviation, not just the hour. "3:00 PM ACST" is unambiguous; "3 PM" across a -5h 30m gap is not.
- Block 2:30 PM–5:00 PM ACST as the recurring meeting window if you work primarily from ACST and need GST colleagues present.
About ACST (Australian Central Standard Time)
Australian Central Standard Time (ACST) is the half-hour offset of UTC+09:30 used across South Australia and the Northern Territory, taking in Adelaide and Darwin. South Australia moves to Australian Central Daylight Time (ACDT, UTC+10:30) from the first Sunday in October to the first Sunday in April, but the Northern Territory does not observe daylight saving — so Adelaide and Darwin sit 30 minutes apart in summer and level with each other in winter. The half-hour offset means Adelaide is 30 minutes behind Sydney in winter and level with it during daylight saving, which regularly catches out travellers and meeting planners.
About GST (Gulf Standard Time)
Gulf Standard Time (GST) is the time zone used in the United Arab Emirates, Oman, and other Gulf states. GST does not observe daylight saving time. Dubai and Abu Dhabi, major international business and tourism hubs, operate on GST.
Best time to call between ACST and GST
Both ACST and GST sit inside the 9 AM – 5 PM working day between 2:30 PM–5:00 PM ACST, which is 9:00 AM–11:30 AM GST. That gives roughly 2 hours and 30 minutes of shared time — the safest window for a live call or meeting.
Business hours overlap
ACST and GST overlap for about 2 hours during the working day — enough for meetings if you avoid the edges of the window.
ACST is 5 hours 30 minutes behind GST (ACST UTC+09:30 → GST UTC+04:00). The shared working window is 2:30 PM–5:00 PM ACST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
ACST
❄ Currently in Standard Time
Standard: UTC+09:30 · DST: UTC+10:30
Clocks spring forward on Sat, Oct 3, 2026
GST
Does not observe DST
Learn More About Time
Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:
Frequently Asked Questions
What is the time difference between ACST and GST?
ACST (ACST, UTC+09:30) is 5 hours 30 minutes behind GST (GST, UTC+04:00). The gap is currently -5h 30m.
How do I convert ACST time to GST time?
Add -5h 30m to ACST local time. For example, 9:00 AM in ACST is 3:30 AM in GST.
What time is it in GST right now?
GST uses GST at UTC+04:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -5h 30m offset from ACST.
What is the best time to call GST from ACST?
Call between 2:30 PM and 5:00 PM ACST — that maps to 9:00 AM–11:30 AM GST and keeps both parties inside the working day.
Which is behind, ACST or GST?
ACST is 5 hours 30 minutes behind GST. When it is 12:00 PM in ACST it is 6:30 AM in GST.
Does daylight saving time affect the ACST–GST difference?
Neither zone observes daylight saving time, so the -5h 30m offset between ACST and GST is fixed all year.
Which other cities share ACST's time zone?
ACST also covers Adelaide, Darwin, Alice Springs, Mount Gambier.
Which countries use ACST, ACST's zone?
ACST is used in Australia (South Australia, Northern Territory).
Is there a day difference between ACST and GST?
Not normally. The -5h 30m gap only pushes the date over the previous day.
What is the time difference between ACST and GST?
GST is -5h 30m from ACST.
What timezone is ACST in?
ACST operates on its local timezone.
What timezone is GST in?
GST operates on its local timezone.
Which countries use ACST (Australian Central Standard Time)?
ACST is used in Australia (South Australia, Northern Territory).
Does ACST observe daylight saving time?
Yes, ACST switches to ACDT during summer months.
What are some interesting facts about ACST?
ACST uses a half-hour offset: UTC+09:30. South Australia moves to ACDT (UTC+10:30) in summer; the Northern Territory does not.
Which cities are in the GST timezone?
Major cities in the GST timezone include Dubai, Abu Dhabi, Muscat, Baku, Tbilisi.
What is the UTC offset for GST?
Gulf Standard Time (GST) is at UTC+04:00.
What should I know about the GST timezone?
Dubai uses GST year-round with no daylight saving time. GST is 9 hours ahead of EST and 4 hours ahead of GMT.
When is it midnight in ACST, what time is it in GST?
When it is 12:00 AM (midnight) in ACST (ACST), it is -5h 30m later in GST (GST).
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See every conversion from ACST →·See every conversion from GST →