AST to PDT Converter
Convert time between Atlantic Standard Time (AST) and Pacific Daylight Time (PDT)
Atlantic Standard Time (AST)
Pacific Daylight Time (PDT)
Time Difference
Pacific Daylight Time (PDT) is 0 hours ahead of Atlantic Standard Time (AST)
Select Date
Select Time
Quick Reference
| AST | PDT |
|---|---|
| 22:00 | 18:00 |
| 00:00 | 20:00 |
| 02:00 | 22:00 |
| 04:00 | 00:00 |
| 06:00 | 02:00 |
| 08:00 | 04:00 |
| 10:00 | 06:00 |
| 12:00 | 08:00 |
| 14:00 | 10:00 |
| 16:00 | 12:00 |
| 18:00 | 14:00 |
| 20:00 | 16:00 |
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
Related Time Zone Conversions
About AST to PDT Time Conversion
Converting time between Atlantic Standard Time (AST) and Pacific Daylight Time (PDT) is essential for coordinating across North America from Atlantic Canada to the US Pacific Coast. AST is UTC-4 (the standard time in Atlantic Canada, used November to March), while PDT is UTC-7 (used March to November on the US Pacific coast). AST is 3 hours ahead of PDT.
This conversion is crucial for business coordination between Atlantic Canada and the US West Coast, travel planning, and communication across these distant regions. Understanding the 3-hour time difference helps ensure accurate scheduling for business meetings, family calls, and coordinated activities spanning both coasts of North America. Note that from March to November, when Atlantic Daylight Time (ADT) is active, the difference becomes 2 hours.
Common Use Cases for AST to PDT Conversion
Business & Work
- Scheduling meetings between Atlantic Canada and Pacific Coast offices
- Coordinating with Pacific West Coast business partners and clients
- Planning conference calls across Atlantic and Pacific time zones
- Managing distributed teams across North American coasts
Personal & Travel
- Coordinating with family and friends in Pacific Coast regions
- Planning travel from Atlantic Canada to Pacific Coast destinations
- Scheduling events that include participants from both regions
- Understanding time differences for remote communications
Time Zone Information
Atlantic Standard Time (AST)
- UTC Offset: UTC-4 (UTC-3 during ADT)
- IANA Timezone: America/Halifax
- Daylight Saving: Second Sunday in March to First Sunday in November
- Major Cities: Halifax, Saint John, Charlottetown, Fredericton
- Coverage: Atlantic Canada (Nova Scotia, New Brunswick, Prince Edward Island)
Pacific Daylight Time (PDT)
- UTC Offset: UTC-7 (UTC-8 during PST)
- IANA Timezone: America/Los_Angeles
- Daylight Saving: Second Sunday in March to First Sunday in November
- Major Cities: Los Angeles, San Francisco, Seattle, San Diego, Portland, Vancouver
- Coverage: Pacific United States and Canada
Quick Reference: AST to PDT
Remember: AST is 3 hours ahead of PDT during winter (November-March). From March to November when ADT is active, the difference becomes 2 hours (ADT to PDT).
Frequently Asked Questions
What is the time difference between AST and PDT?
Atlantic Standard Time (AST) is UTC-4, while Pacific Daylight Time (PDT) is UTC-7. This means AST is 3 hours ahead of PDT. When it's 12:00 PM (noon) in Halifax (AST), it's 9:00 AM in Los Angeles (PDT). Note: Atlantic Standard Time is observed during winter, and the offset changes to 2 hours when Atlantic Daylight Time (ADT, UTC-3) is active.
How does the AST to PDT offset differ from other timezone conversions?
The 3-hour offset between AST and PDT is more manageable than many Atlantic to US West Coast conversions. This occurs during the specific period when AST is active (winter months, November to March) while PDT is observed (March to November). The offset becomes 2 hours from March to November when both regions have daylight time active (ADT and PDT). This variation makes seasonal awareness important for scheduling.
Does Atlantic Canada observe daylight saving time like PDT does?
Yes, Atlantic Canada transitions to Atlantic Daylight Time (ADT, UTC-3) on the second Sunday in March and returns to Atlantic Standard Time (AST, UTC-4) on the first Sunday in November. During daylight saving time periods (March to November), the difference between Atlantic and Pacific becomes 2 hours (ADT to PDT). This makes winter months the only period when the true AST-to-PDT offset of 3 hours applies.
When does the time difference change from 3 to 2 hours?
The difference changes on the second Sunday in March when Atlantic Standard Time (AST) transitions to Atlantic Daylight Time (ADT). From March to November (when both ADT and PDT are active), the difference is 2 hours. From November to March (when AST and PDT are active), the difference is 3 hours. Both regions transition to daylight time on the same date, simplifying calendar management.
What are the best times to schedule calls between Atlantic Canada and Pacific US?
With a 3-hour offset (winter) or 2-hour offset (summer), business hour overlap is moderate. Atlantic morning (9 AM-12 PM AST) overlaps with Pacific early morning (6 AM-9 AM PDT). Pacific afternoon (2 PM-5 PM PDT) overlaps with Atlantic evening (5 PM-8 PM AST). For winter months, early Atlantic morning (8-9 AM AST) provides a comfortable window for Pacific teams starting their day (5-6 AM PDT).
Why coordinate between Atlantic Canada and Pacific regions?
Atlantic Canada and the US Pacific region represent two major economic hubs with significant tech, finance, and business operations. The 3-hour winter offset makes coordination more feasible than many other Atlantic-Pacific pairs. Major cities like Halifax and Vancouver form natural business corridors. With proper scheduling awareness, teams can maintain effective collaboration despite the multi-hour difference across North America.
Pro Tips
- • Remember the 3-hour offset (winter) or 2-hour offset (summer). The difference changes only on daylight saving transition dates.
- • Both regions transition on the same date (second Sunday in March, first Sunday in November). Mark these dates to immediately adjust your meeting schedules.
- • Schedule Atlantic team meetings at 8-9 AM AST to catch Pacific teams at 5-6 AM PDT for early risers or overnight shifts.
- • Use the 2-4 PM PDT window (4-6 PM ADT in summer) for discussions when both regions are in the afternoon workday.
- • During winter (AST-PDT, 3-hour difference), 9 AM AST equals 6 AM PDT - better for Pacific West Coast early schedules.
- • Document all meeting times in both AST and PDT, noting whether daylight saving time is active to prevent confusion during transitions.
Update Logs
View the latest updates and features