GST to ACST
+5h 30mGST
GSTSOURCEACST
ACSTGreen rows indicate typical business hours (9 AM - 5 PM)
GST and ACST on the World Map
The map below highlights the GST (Gulf Standard Time) and ACST (Australian Central Standard Time) timezone regions across the globe.
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.
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 to ACST Time Difference – Complete Guide
GST runs on Gulf Standard Time (GST) at UTC+04:00. ACST runs on Australian Central Standard Time (ACST) at UTC+09:30. That puts GST 5 hours 30 minutes ahead of ACST — a difference of +5h 30m at the current offsets.
In practice, when it is 9:00 AM in GST it is 2:30 PM in ACST. Midnight in GST is 5:30 AM in ACST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
GST to ACST time conversion table
| GST (GST) | ACST (ACST) | Day |
|---|---|---|
| 12:00 AM | 5:30 AM | same day |
| 6:00 AM | 11:30 AM | same day |
| 7:00 AM | 12:30 PM | same day |
| 8:00 AM | 1:30 PM | same day |
| 9:00 AM | 2:30 PM | same day |
| 12:00 PM | 5:30 PM | same day |
| 3:00 PM | 8:30 PM | same day |
| 5:00 PM | 10:30 PM | same day |
| 6:00 PM | 11:30 PM | same day |
| 9:00 PM | 2:30 AM | next day |
Why people convert GST to ACST time
- Scheduling a call from GST to ACST: a 10:00 AM start in GST lands at 3:30 PM in ACST, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both GST and ACST are inside the 9-to-5 working day between 9:00 AM and 11:30 AM GST time (2:30 PM–5:00 PM ACST). That is roughly 2 hours 30 minutes of usable overlap.
- Coordinating a GST-based team with ACST contacts: quoting times in the other side's local clock — not your own — removes the single biggest source of missed meetings.
- Always state the zone abbreviation, not just the hour. "3:00 PM GST" is unambiguous; "3 PM" across a +5h 30m gap is not.
- Block 9:00 AM–11:30 AM GST as the recurring meeting window if you work primarily from GST and need ACST colleagues present.
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.
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.
Best time to call between GST and ACST
Both GST and ACST sit inside the 9 AM – 5 PM working day between 9:00 AM–11:30 AM GST, which is 2:30 PM–5:00 PM ACST. That gives roughly 2 hours and 30 minutes of shared time — the safest window for a live call or meeting.
Business hours overlap
GST and ACST overlap for about 2 hours during the working day — enough for meetings if you avoid the edges of the window.
GST is 5 hours 30 minutes ahead of ACST (GST UTC+04:00 → ACST UTC+09:30). The shared working window is 9:00 AM–11:30 AM GST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
GST
Does not observe DST
ACST
❄ Currently in Standard Time
Standard: UTC+09:30 · DST: UTC+10:30
Clocks spring forward on Sat, Oct 3, 2026
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 GST and ACST?
GST (GST, UTC+04:00) is 5 hours 30 minutes ahead of ACST (ACST, UTC+09:30). The gap is currently +5h 30m.
How do I convert GST time to ACST time?
Add +5h 30m to GST local time. For example, 9:00 AM in GST is 2:30 PM in ACST.
What time is it in ACST right now?
ACST uses ACST at UTC+09:30. Use the live converter at the top of this page — it updates in real time and already accounts for the +5h 30m offset from GST.
What is the best time to call ACST from GST?
Call between 9:00 AM and 11:30 AM GST — that maps to 2:30 PM–5:00 PM ACST and keeps both parties inside the working day.
Which is ahead, GST or ACST?
GST is 5 hours 30 minutes ahead of ACST. When it is 12:00 PM in GST it is 5:30 PM in ACST.
Does daylight saving time affect the GST–ACST difference?
Neither zone observes daylight saving time, so the +5h 30m offset between GST and ACST is fixed all year.
Which other cities share GST's time zone?
GST also covers Dubai, Abu Dhabi, Muscat, Baku, Tbilisi.
Which countries use GST, GST's zone?
GST is used in UAE, Oman, Georgia, Azerbaijan, Mauritius.
Is there a day difference between GST and ACST?
Not normally. The +5h 30m gap only pushes the date over for late-evening times.
What is the time difference between GST and ACST?
ACST is +5h 30m from GST.
What timezone is GST in?
GST operates on its local timezone.
What timezone is ACST in?
ACST operates on its local timezone.
Which countries use GST (Gulf Standard Time)?
GST is used in UAE, Oman, Georgia, Azerbaijan, Mauritius.
Does GST observe daylight saving time?
No, GST does not observe daylight saving time and remains at UTC+04:00 year-round.
What are some interesting facts about GST?
Dubai uses GST year-round with no daylight saving time. GST is 9 hours ahead of EST and 4 hours ahead of GMT.
Which cities are in the ACST timezone?
Major cities in the ACST timezone include Adelaide, Darwin, Alice Springs, Mount Gambier.
What is the UTC offset for ACST?
Australian Central Standard Time (ACST) is at UTC+09:30. During daylight saving time, it shifts to ACDT.
What should I know about the ACST timezone?
ACST uses a half-hour offset: UTC+09:30. South Australia moves to ACDT (UTC+10:30) in summer; the Northern Territory does not.
When is it midnight in GST, what time is it in ACST?
When it is 12:00 AM (midnight) in GST (GST), it is +5h 30m later in ACST (ACST).
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