ICT to AST
-11hICT
ICTSOURCEAST
ASTGreen rows indicate typical business hours (9 AM - 5 PM)
ICT and AST on the World Map
The map below highlights the ICT (Indochina Time) and AST (Atlantic Standard Time) timezone regions across the globe.
ICT – Indochina Time
UTC+07:00Indochina Time (ICT) is the time zone for Vietnam, Thailand, Laos, and Cambodia, 7 hours ahead of UTC.
- •Bangkok is one of the most visited cities in the world.
- •ICT is 12 hours ahead of EST.
- •Thailand, Vietnam, and Cambodia all share ICT.
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.
Understanding the -11h Gap: ICT vs AST
ICT runs on Indochina Time (ICT) at UTC+07:00. AST runs on Atlantic Standard Time (AST) at UTC-04:00. That puts ICT 11 hours behind AST — a difference of -11h at the current offsets.
In practice, when it is 9:00 AM in ICT it is 10:00 PM in AST on the previous day. Midnight in ICT is 1:00 PM in AST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
ICT to AST time conversion table
| ICT (ICT) | AST (AST) | Day |
|---|---|---|
| 12:00 AM | 1:00 PM | previous day |
| 6:00 AM | 7:00 PM | previous day |
| 7:00 AM | 8:00 PM | previous day |
| 8:00 AM | 9:00 PM | previous day |
| 9:00 AM | 10:00 PM | previous day |
| 12:00 PM | 1:00 AM | same day |
| 3:00 PM | 4:00 AM | same day |
| 5:00 PM | 6:00 AM | same day |
| 6:00 PM | 7:00 AM | same day |
| 9:00 PM | 10:00 AM | same day |
Why people convert ICT to AST time
- Scheduling a call from ICT to AST: a 10:00 AM start in ICT lands at 11:00 PM in AST the previous day, so you can confirm the slot without doing the arithmetic yourself.
- Handling a -11h gap: ICT and AST 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 AST is 10:00 PM in ICT.
- Coordinating a ICT-based team with AST 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 ICT" is unambiguous; "3 PM" across a -11h gap is not.
- With a -11h gap there is no shared 9-to-5 window, so alternate the early start: one week ICT takes the early slot, the next week AST does.
About ICT (Indochina Time)
Indochina Time (ICT) is used across Southeast Asia including Vietnam, Thailand, Laos, and Cambodia. Indonesia (Western time, WIB) also uses UTC+07:00. ICT does not observe daylight saving time.
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.
Best time to call between ICT and AST
With a -11h offset there is no overlap inside a normal 9 AM – 5 PM day. AST opens at 9:00 AM AST, which is 10:00 PM in ICT, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
ICT and AST have no shared working hours because of the -11h gap. Teams need to alternate early starts or rely on asynchronous handovers.
ICT is 11 hours behind AST (ICT UTC+07:00 → AST UTC-04:00). 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
ICT
Does not observe DST
AST
☀ Currently in DST
Standard: UTC-04:00 · DST: UTC-03:00
Clocks fall back on Sun, Nov 1, 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 ICT and AST?
ICT (ICT, UTC+07:00) is 11 hours behind AST (AST, UTC-04:00). The gap is currently -11h.
How do I convert ICT time to AST time?
Add -11h to ICT local time. For example, 9:00 AM in ICT is 10:00 PM in AST (previous day).
What time is it in AST right now?
AST uses AST at UTC-04:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -11h offset from ICT.
What is the best time to call AST from ICT?
There is no shared working-hours window because of the -11h gap. The closest option is 1:00 PM in ICT, which is 2:00 AM in AST.
Which is behind, ICT or AST?
ICT is 11 hours behind AST. When it is 12:00 PM in ICT it is 1:00 AM in AST.
Does daylight saving time affect the ICT–AST difference?
Neither zone observes daylight saving time, so the -11h offset between ICT and AST is fixed all year.
Which other cities share ICT's time zone?
ICT also covers Bangkok, Ho Chi Minh City, Hanoi, Jakarta, Phnom Penh, Vientiane.
Which countries use ICT, ICT's zone?
ICT is used in Thailand, Vietnam, Cambodia, Laos, Indonesia (WIB).
Is there a day difference between ICT and AST?
Not normally. The -11h gap only pushes the date over the previous day.
What is the time difference between ICT and AST?
AST is -11h from ICT.
What timezone is ICT in?
ICT operates on its local timezone.
What timezone is AST in?
AST operates on its local timezone.
Which countries use ICT (Indochina Time)?
ICT is used in Thailand, Vietnam, Cambodia, Laos, Indonesia (WIB).
Does ICT observe daylight saving time?
No, ICT does not observe daylight saving time and remains at UTC+07:00 year-round.
What are some interesting facts about ICT?
Bangkok is one of the most visited cities in the world. ICT is 12 hours ahead of EST.
Which cities are in the AST timezone?
Major cities in the AST timezone include Halifax, San Juan, Santo Domingo, Caracas, La Paz, Fredericton, Charlottetown.
What is the UTC offset for AST?
Atlantic Standard Time (AST) is at UTC-04:00. During daylight saving time, it shifts to ADT.
What should I know about the AST timezone?
Puerto Rico uses AST year-round and does not observe DST. AST is 1 hour ahead of EST.
When is it midnight in ICT, what time is it in AST?
When it is 12:00 AM (midnight) in ICT (ICT), it is -11h later in AST (AST).
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See every conversion from ICT →·See every conversion from AST →