SGT to AST
-12hSGT
SGTSOURCEAST
ASTGreen rows indicate typical business hours (9 AM - 5 PM)
SGT and AST on the World Map
The map below highlights the SGT (Singapore Standard Time) and AST (Atlantic Standard Time) timezone regions across the globe.
SGT – Singapore Standard Time
UTC+08:00Singapore Standard Time (SGT) is the time zone for Singapore, 8 hours ahead of UTC.
- •Singapore uses UTC+08:00 despite being at about 104°E longitude (closer to UTC+07:00).
- •Singapore does not observe daylight saving time.
- •The Singapore Exchange (SGX) operates on SGT.
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.
SGT vs AST: Offsets, DST and Best Call Times
SGT runs on Singapore Standard Time (SGT) at UTC+08:00. AST runs on Atlantic Standard Time (AST) at UTC-04:00. That puts SGT 12 hours behind AST — a difference of -12h at the current offsets.
In practice, when it is 9:00 AM in SGT it is 9:00 PM in AST on the previous day. Midnight in SGT is 12:00 PM in AST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
SGT to AST time conversion table
| SGT (SGT) | AST (AST) | Day |
|---|---|---|
| 12:00 AM | 12:00 PM | previous day |
| 6:00 AM | 6:00 PM | previous day |
| 7:00 AM | 7:00 PM | previous day |
| 8:00 AM | 8:00 PM | previous day |
| 9:00 AM | 9:00 PM | previous day |
| 12:00 PM | 12:00 AM | same day |
| 3:00 PM | 3:00 AM | same day |
| 5:00 PM | 5:00 AM | same day |
| 6:00 PM | 6:00 AM | same day |
| 9:00 PM | 9:00 AM | same day |
Why people convert SGT to AST time
- Scheduling a call from SGT to AST: a 10:00 AM start in SGT lands at 10:00 PM in AST the previous day, so you can confirm the slot without doing the arithmetic yourself.
- Handling a -12h gap: SGT 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 9:00 PM in SGT.
- Booking travel or deliveries: tracking AST local time against SGT keeps pickup windows and arrival estimates honest across the -12h offset.
- Always state the zone abbreviation, not just the hour. "3:00 PM SGT" is unambiguous; "3 PM" across a -12h gap is not.
- With a -12h gap there is no shared 9-to-5 window, so alternate the early start: one week SGT takes the early slot, the next week AST does.
About SGT (Singapore Standard Time)
Singapore Standard Time (SGT) is used in Singapore year-round. Singapore does not observe daylight saving time. Despite being geographically close to the UTC+07:00 zone, Singapore uses UTC+08:00 to align with major trading partners like China, Hong Kong, and Malaysia. Singapore is a major global financial hub.
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 SGT and AST
With a -12h offset there is no overlap inside a normal 9 AM – 5 PM day. AST opens at 9:00 AM AST, which is 9:00 PM in SGT, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
SGT and AST have no shared working hours because of the -12h gap. Teams need to alternate early starts or rely on asynchronous handovers.
SGT is 12 hours behind AST (SGT UTC+08:00 → 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
SGT
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 SGT and AST?
SGT (SGT, UTC+08:00) is 12 hours behind AST (AST, UTC-04:00). The gap is currently -12h.
How do I convert SGT time to AST time?
Add -12h to SGT local time. For example, 9:00 AM in SGT is 9:00 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 -12h offset from SGT.
What is the best time to call AST from SGT?
There is no shared working-hours window because of the -12h gap. The closest option is 1:00 PM in SGT, which is 1:00 AM in AST.
Which is behind, SGT or AST?
SGT is 12 hours behind AST. When it is 12:00 PM in SGT it is 12:00 AM in AST.
Does daylight saving time affect the SGT–AST difference?
Neither zone observes daylight saving time, so the -12h offset between SGT and AST is fixed all year.
Which other cities share SGT's time zone?
SGT also covers Singapore.
Which countries use SGT, SGT's zone?
SGT is used in Singapore.
Is there a day difference between SGT and AST?
Sometimes. The -12h gap is large enough that 8:00 PM or later in SGT already falls on the in AST.
What is the time difference between SGT and AST?
AST is -12h from SGT.
What timezone is SGT in?
SGT operates on its local timezone.
What timezone is AST in?
AST operates on its local timezone.
Which countries use SGT (Singapore Standard Time)?
SGT is used in Singapore.
Does SGT observe daylight saving time?
No, SGT does not observe daylight saving time and remains at UTC+08:00 year-round.
What are some interesting facts about SGT?
Singapore uses UTC+08:00 despite being at about 104°E longitude (closer to UTC+07:00). Singapore does not observe daylight saving time.
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 SGT, what time is it in AST?
When it is 12:00 AM (midnight) in SGT (SGT), it is -12h later in AST (AST).
Related Developer Tools
Explore more tools that work great with timezone conversions for international teams:
Related Timezone Conversions
More SGT time conversions
- sgt to singapore
- sgt to new york
- sgt to london
- sgt to dubai
- sgt to tokyo
- sgt to sydney
- sgt to los angeles
- sgt to paris
- sgt to delhi
- sgt to mumbai
- sgt to berlin
- sgt to hong kong
- sgt to toronto
- sgt to kathmandu
- new york to sgt
- london to sgt
- dubai to sgt
- tokyo to sgt
- singapore to sgt
- sydney to sgt
- los angeles to sgt
- paris to sgt
- delhi to sgt
- mumbai to sgt
- berlin to sgt
- hong kong to sgt
- toronto to sgt
- kathmandu to sgt
See every conversion from SGT →·See every conversion from AST →