SGT to AST Converter
Convert time between Singapore Standard Time (SGT) and Atlantic Standard Time (AST)
Singapore Standard Time (SGT)
Atlantic Standard Time (AST)
Time Difference
Atlantic Standard Time (AST) is 0 hours ahead of Singapore Standard Time (SGT)
Select Date
Select Time
Quick Reference
| SGT | AST |
|---|---|
| 10:00 | 23:00 |
| 12:00 | 01:00 |
| 14:00 | 03:00 |
| 16:00 | 05:00 |
| 18:00 | 07:00 |
| 20:00 | 09:00 |
| 22:00 | 11:00 |
| 00:00 | 13:00 |
| 02:00 | 15:00 |
| 04:00 | 17:00 |
| 06:00 | 19:00 |
| 08:00 | 21:00 |
Top 10 Most Common Time Zones
| Abbreviation | Full Name | UTC Offset | Typical Use |
|---|---|---|---|
| UTC | Coordinated Universal Time | UTC ±0 | Global reference standard (servers, logs, APIs) |
| EST / EDT | Eastern (US) Time | UTC −5 / −4 | New York, Toronto — North American business hub |
| CST / CDT | Central (US) Time | UTC −6 / −5 | Chicago, Dallas — US central business region |
| PST / PDT | Pacific (US) Time | UTC −8 / −7 | San Francisco, Los Angeles — tech industry standard |
| GMT / BST | Greenwich Mean / British Summer Time | UTC 0 / +1 | UK, used globally as a reference with UTC |
| CET / CEST | Central European (Summer) Time | UTC +1 / +2 | Paris, Berlin, Amsterdam — EU business core |
| IST | India Standard Time | UTC +5:30 | India — major IT & outsourcing region |
| CST | China Standard Time | UTC +8 | Beijing, Shanghai — East Asia business hub |
| JST | Japan Standard Time | UTC +9 | Tokyo — finance & tech hub |
| AEST / AEDT | Australian Eastern (Daylight) Time | UTC +10 / +11 | Sydney, Melbourne — APAC regional business |
Why Time Zone Abbreviations Are Ambiguous
Unlike standardized identifiers (like America/New_York or Europe/London from the IANA tz database), abbreviations such as "CST" or "IST" are not globally unique. They can refer to different time zones depending on context — country, region, or even time of year (due to daylight saving time).
Common Ambiguous Time Zone Abbreviations
| Abbrev. | Common Meaning(s) | UTC Offset | Region(s) |
|---|---|---|---|
| CST | Central Standard Time / China Standard Time / Cuba Standard Time | UTC−6 / UTC+8 / UTC−5 | North America, China, Cuba |
| IST | Indian Standard Time / Irish Standard Time / Israel Standard Time | UTC+5:30 / UTC+1 / UTC+2 | India, Ireland, Israel |
| AST | Atlantic Standard Time / Arabia Standard Time | UTC−4 / UTC+3 | Caribbean, Canada, Middle East |
| PST | Pacific Standard Time / Philippine Standard Time | UTC−8 / UTC+8 | North America, Philippines |
| EST | Eastern Standard Time (North America / Australia) | UTC−5 / UTC+10 | North America, Australia |
✅ Best Practice
To avoid ambiguity, always:
- Use IANA tz identifiers — e.g.,
America/New_Yorkinstead of "EST" - Specify UTC offset explicitly — e.g.,
UTC−5when abbreviations must be used - Include the full timezone name — e.g., "Eastern Standard Time (EST)" with UTC offset
About SGT to AST Time Conversion
Converting time between Singapore Standard Time (SGT) and Atlantic Standard Time (AST) bridges Southeast Asia and the western Atlantic. SGT is UTC+8 year-round, while AST is UTC-4, putting Singapore exactly 12 hours ahead of Atlantic time. The clean 12-hour offset makes the clock easy: just flip AM and PM, but verify the date.
This time zone converter uses the IANA timezone database to ensure accurate calculations. The Canadian Maritimes (Nova Scotia, New Brunswick, Prince Edward Island) observe AST in winter and switch to ADT (UTC-3) from March to November. Most Caribbean territories that use AST never switch, including Puerto Rico, the Dominican Republic and the US Virgin Islands. Whether you're scheduling Singapore-Halifax calls in winter or coordinating with year-round AST regions, our converter clarifies the math.
Common Use Cases for SGT to AST Conversion
Business & Work
- Scheduling winter calls between Singapore and Halifax or Saint John
- Coordinating with year-round AST regions like Puerto Rico or the Dominican Republic
- Planning conference calls with Maritime Canadian partners during AST months
Personal & Travel
- Planning travel between Singapore and the Canadian Maritimes or Caribbean
- Coordinating with family and friends in Halifax, San Juan or Santo Domingo
- Scheduling virtual events bridging Asia and the Atlantic
Time Zone Information
Singapore Standard Time (SGT)
- UTC Offset: UTC+8
- IANA Timezone: Asia/Singapore
- Daylight Saving: No daylight saving time (consistent year-round)
- Major Cities: Singapore
- Coverage: Republic of Singapore
Atlantic Standard Time (AST)
- UTC Offset: UTC-4 (UTC-3 ADT in Maritime Canada during summer)
- IANA Timezone: America/Halifax
- Daylight Saving: Maritime Canada observes ADT from second Sunday in March to first Sunday in November; Caribbean AST regions usually stay on AST year-round
- Major Cities: Halifax, Saint John, Charlottetown, San Juan, Santo Domingo, Bridgetown
- Coverage: Canadian Maritime provinces, Bermuda, Puerto Rico, US Virgin Islands, Dominican Republic and most eastern Caribbean nations
Quick Reference: SGT to AST
Remember: AST is 12 hours behind SGT. In Maritime Canada, summer ADT (UTC-3) shrinks the gap to 11 hours. Most Caribbean AST regions keep the 12-hour offset all year.
Frequently Asked Questions
What is the time difference between SGT and AST?
Singapore Standard Time (SGT) is UTC+8, while Atlantic Standard Time (AST) is UTC-4. SGT is 12 hours ahead of AST. When it is 12:00 PM in Singapore, it is 12:00 AM the same day in Halifax or San Juan.
Is AST the same as Arabia Standard Time?
No. On this site AST refers strictly to Atlantic Standard Time (UTC-4), covering the Canadian Maritimes and several Caribbean territories. Arabia Standard Time is a different zone at UTC+3.
When does AST give way to ADT?
In Maritime Canada (Nova Scotia, New Brunswick, PEI), AST switches to ADT (UTC-3) from the second Sunday in March to the first Sunday in November, shrinking the SGT gap to 11 hours. Most Caribbean AST regions (Puerto Rico, Dominican Republic, US Virgin Islands) never switch.
What are the best times for SGT-AST business calls?
The 12-hour gap is roughly inverted. Singapore evening (8:00 to 10:00 PM SGT) is Atlantic morning (8:00 to 10:00 AM AST). Singapore morning (8:00 to 10:00 AM SGT) reaches Atlantic evening (8:00 to 10:00 PM AST).
Which countries or regions use AST?
AST covers the Canadian Maritime provinces (Nova Scotia, New Brunswick, Prince Edward Island), Bermuda, Puerto Rico, the US Virgin Islands, the Dominican Republic, Barbados and most other eastern Caribbean nations.
Which countries or regions use SGT?
Singapore Standard Time is used only in the Republic of Singapore. UTC+8 is shared with Malaysia (MYT), Western Australia (AWST), Hong Kong, the Philippines and most of mainland China.
Pro Tips
- • AST is 12 hours behind SGT — flip AM and PM and keep the same date for the easy mental shortcut.
- • During Maritime Canadian summer (ADT, March to November), the gap shrinks to 11 hours. Caribbean AST regions usually do not change.
- • Singapore stays on UTC+8 year-round, so all seasonal offset variation comes from the AST side.
- • For year-round Caribbean contacts (Puerto Rico, Dominican Republic), the 12-hour gap is a stable anchor.
- • Singapore evening (8:00 to 11:00 PM SGT) is the cleanest overlap with Atlantic morning business hours.
- • Use IANA identifiers Asia/Singapore and America/Halifax (or America/Puerto_Rico for the Caribbean) in calendars.