AST to ACST
+13h 30mAST
ASTSOURCEACST
ACSTGreen rows indicate typical business hours (9 AM - 5 PM)
AST and ACST on the World Map
The map below highlights the AST (Atlantic Standard Time) and ACST (Australian Central Standard Time) timezone regions across the globe.
AST – Atlantic Standard Time
UTC-04:00Atlantic Standard Time (AST) is the time zone for the Canadian Atlantic provinces and the Caribbean, 4 hours behind UTC.
- •Puerto Rico uses AST year-round and does not observe DST.
- •AST is 1 hour ahead of EST.
- •Halifax, the capital of Nova Scotia, is the largest city in AST Canada.
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.
AST to ACST Time Difference – Complete Guide
AST runs on Atlantic Standard Time (AST) at UTC-04:00. ACST runs on Australian Central Standard Time (ACST) at UTC+09:30. That puts AST 13 hours 30 minutes ahead of ACST — a difference of +13h 30m at the current offsets.
In practice, when it is 9:00 AM in AST it is 10:30 PM in ACST. Midnight in AST is 1:30 PM in ACST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
AST to ACST time conversion table
| AST (AST) | ACST (ACST) | Day |
|---|---|---|
| 12:00 AM | 1:30 PM | same day |
| 6:00 AM | 7:30 PM | same day |
| 7:00 AM | 8:30 PM | same day |
| 8:00 AM | 9:30 PM | same day |
| 9:00 AM | 10:30 PM | same day |
| 12:00 PM | 1:30 AM | next day |
| 3:00 PM | 4:30 AM | next day |
| 5:00 PM | 6:30 AM | next day |
| 6:00 PM | 7:30 AM | next day |
| 9:00 PM | 10:30 AM | next day |
Why people convert AST to ACST time
- Scheduling a call from AST to ACST: a 10:00 AM start in AST lands at 11:30 PM in ACST, so you can confirm the slot without doing the arithmetic yourself.
- Handling a +13h 30m gap: AST and ACST have no overlap inside a normal 9-to-5 day, so real-time meetings need an early-morning or late-evening slot on one side. 9:00 AM in ACST is 10:30 PM in AST.
- Booking travel or deliveries: tracking ACST local time against AST keeps pickup windows and arrival estimates honest across the +13h 30m offset.
- Always state the zone abbreviation, not just the hour. "3:00 PM AST" is unambiguous; "3 PM" across a +13h 30m gap is not.
- With a +13h 30m gap there is no shared 9-to-5 window, so alternate the early start: one week AST takes the early slot, the next week ACST does.
About AST (Atlantic Standard Time)
Atlantic Standard Time (AST) covers Canada's Atlantic provinces (Nova Scotia, New Brunswick, Prince Edward Island, and most of Labrador), as well as several Caribbean nations. Puerto Rico and the US Virgin Islands use AST year-round without daylight saving time. The Canadian provinces switch to Atlantic Daylight Time (ADT) in summer.
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 AST and ACST
With a +13h 30m offset there is no overlap inside a normal 9 AM – 5 PM day. ACST opens at 9:00 AM ACST, which is 10:30 PM in AST, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
AST and ACST have no shared working hours because of the +13h 30m gap. Teams need to alternate early starts or rely on asynchronous handovers.
AST is 13 hours 30 minutes ahead of ACST (AST UTC-04:00 → ACST UTC+09:30). There is no shared 9-to-5 window, so plan around an early or late slot. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
AST
☀ Currently in DST
Standard: UTC-04:00 · DST: UTC-03:00
Clocks fall back on Sun, Nov 1, 2026
ACST
❄ Currently in Standard Time
Standard: UTC+09:30 · DST: UTC+10:30
Clocks spring forward on Sat, Oct 3, 2026
⚠ These locations are currently in different DST states, so the time difference may change when clocks adjust.
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 AST and ACST?
AST (AST, UTC-04:00) is 13 hours 30 minutes ahead of ACST (ACST, UTC+09:30). The gap is currently +13h 30m.
How do I convert AST time to ACST time?
Add +13h 30m to AST local time. For example, 9:00 AM in AST is 10:30 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 +13h 30m offset from AST.
What is the best time to call ACST from AST?
There is no shared working-hours window because of the +13h 30m gap. The closest option is 1:00 PM in AST, which is 2:30 AM in ACST.
Which is ahead, AST or ACST?
AST is 13 hours 30 minutes ahead of ACST. When it is 12:00 PM in AST it is 1:30 AM in ACST.
Does daylight saving time affect the AST–ACST difference?
Neither zone observes daylight saving time, so the +13h 30m offset between AST and ACST is fixed all year.
Which other cities share AST's time zone?
AST also covers Halifax, San Juan, Santo Domingo, Caracas, La Paz, Fredericton, Charlottetown.
Which countries use AST, AST's zone?
AST is used in Canada (Atlantic provinces), Puerto Rico, US Virgin Islands, Dominican Republic, Venezuela, Bolivia, Barbados, Trinidad and Tobago.
Is there a day difference between AST and ACST?
Sometimes. The +13h 30m gap is large enough that 8:00 PM or later in AST already falls on the next day in ACST.
What is the time difference between AST and ACST?
ACST is +13h 30m from AST.
What timezone is AST in?
AST operates on its local timezone.
What timezone is ACST in?
ACST operates on its local timezone.
Which countries use AST (Atlantic Standard Time)?
AST is used in Canada (Atlantic provinces), Puerto Rico, US Virgin Islands, Dominican Republic, Venezuela, Bolivia, and 2 more countries.
Does AST observe daylight saving time?
Yes, AST switches to ADT during summer months.
What are some interesting facts about AST?
Puerto Rico uses AST year-round and does not observe DST. AST is 1 hour ahead of EST.
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 AST, what time is it in ACST?
When it is 12:00 AM (midnight) in AST (AST), it is +13h 30m later in ACST (ACST).
Related Developer Tools
Explore more tools that work great with timezone conversions for international teams:
Related Timezone Conversions
More AST time conversions
- ast to halifax
- ast to new york
- ast to london
- ast to dubai
- ast to tokyo
- ast to singapore
- ast to sydney
- ast to los angeles
- ast to paris
- ast to delhi
- ast to mumbai
- ast to berlin
- ast to hong kong
- ast to toronto
- ast to kathmandu
- new york to ast
- london to ast
- dubai to ast
- tokyo to ast
- singapore to ast
- sydney to ast
- los angeles to ast
- paris to ast
- delhi to ast
- mumbai to ast
- berlin to ast
- hong kong to ast
- toronto to ast
- kathmandu to ast
See every conversion from AST →·See every conversion from ACST →