PDT to AST Converter
Convert time between Pacific Daylight Time (PDT) and Atlantic Standard Time (AST)
Pacific Daylight Time (PDT)
Atlantic Standard Time (AST)
Time Difference
Atlantic Standard Time (AST) is 0 hours ahead of Pacific Daylight Time (PDT)
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Quick Reference
| PDT | AST |
|---|---|
| 18:00 | 22:00 |
| 20:00 | 00:00 |
| 22:00 | 02:00 |
| 00:00 | 04:00 |
| 02:00 | 06:00 |
| 04:00 | 08:00 |
| 06:00 | 10:00 |
| 08:00 | 12:00 |
| 10:00 | 14:00 |
| 12:00 | 16:00 |
| 14:00 | 18:00 |
| 16:00 | 20:00 |
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 PDT to AST Time Conversion
Converting time between Pacific Daylight Time (PDT) and Atlantic Standard Time (AST) is essential for coordinating between the US Pacific Coast and Atlantic Canada. PDT is UTC-7 (used March to November), while AST is UTC-4 (the standard time in Atlantic Canada, which does not observe additional daylight saving changes beyond AST/ADT transitions). AST is 3 hours ahead of PDT, making it important for cross-continental business coordination.
This converter is valuable for businesses operating across North America, particularly those coordinating between West Coast operations (California, Washington, Oregon) and Atlantic Canada (Nova Scotia, New Brunswick, Prince Edward Island, and Newfoundland and Labrador). The 3-hour time difference is manageable for international business operations and helps optimize meeting schedules.
Common Use Cases for PDT to AST Conversion
Business & Work
- Scheduling meetings between Pacific and Atlantic Canada offices
- Coordinating software development across North American time zones
- Managing cross-continental project deadlines
- Planning conference calls between West Coast and Atlantic regions
Personal & Travel
- Planning travel from Pacific region to Atlantic Canada
- Coordinating with family and friends in Atlantic Canada
- Scheduling international events and online meetings
- Understanding time differences for remote work and collaboration
Time Zone Information
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
- Coverage: Pacific United States and Canada
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, St. John's
- Coverage: Atlantic Canada and some Caribbean islands
Quick Reference: PDT to AST
Remember: AST is always 3 hours ahead of PDT during daylight saving time (March-November). Outside these months, use PST-AST which has a 4-hour difference.
Frequently Asked Questions
What is the time difference between PDT and AST?
Pacific Daylight Time (PDT) is UTC-7, while Atlantic Standard Time (AST) is UTC-4. This means AST is 3 hours ahead of PDT. When it's 12:00 PM in Los Angeles (PDT), it's 3:00 PM in Halifax (AST). This 3-hour difference makes Pacific-Atlantic coordination manageable for most business operations.
Why is it AST and not ADT for Atlantic Canada?
Atlantic Canada observes two timezones: Atlantic Standard Time (AST, UTC-4) during winter and Atlantic Daylight Time (ADT, UTC-3) during summer. AST is the standard time used from November to March. During daylight saving time (March to November), Atlantic Canada uses ADT. This converter uses AST as the reference, making it relevant primarily for winter months or when comparing standard times.
What are the major cities in PDT and AST zones?
PDT covers major West Coast cities including Los Angeles, San Francisco, Seattle, San Diego, and Portland. AST covers Atlantic Canadian cities including Halifax, Saint John, Charlottetown, and St. John's. These represent economically important regions spanning North America from the Pacific to the Atlantic coast.
What are the best times to schedule meetings between PDT and AST regions?
The 3-hour difference allows for reasonable business hour overlap. Morning meetings at 8 AM PDT occur at 11 AM AST, ideal for early West Coast meetings. Afternoon meetings at 2 PM PDT occur at 5 PM AST, perfect for East Coast afternoon slots. This range (8 AM-5 PM PDT = 11 AM-8 PM AST) provides good coordination windows for cross-continental business.
How does the time difference change between PST and AST?
When Pacific time is on standard time (PST, UTC-8) and Atlantic Canada is on standard time (AST, UTC-4), the difference is 4 hours. When both are on daylight time (PDT at UTC-7 and ADT at UTC-3), the difference is still 4 hours. However, PDT to AST (daylight to standard) creates the 3-hour difference. During transition weeks, differences may vary.
What industries commonly need PDT to AST conversion?
Technology and software companies with offices in both regions frequently coordinate using this conversion. Financial services, telecommunications, media production, and outsourced business services also operate across these zones. Additionally, tourism, education, and government services often coordinate between Pacific and Atlantic regions for national programs and initiatives.
Pro Tips
- • The 3-hour PDT to AST difference is straightforward: add 3 hours to PDT time to get AST time. This makes mental calculation easier than many other timezone conversions.
- • Remember that Atlantic Canada observes daylight saving time like most of North America. During summer (March-November), use PDT-ADT which still has a 4-hour difference.
- • Use the morning windows (8-11 AM PDT = 11 AM-2 PM AST) for urgent cross-continental calls that require both parties to be alert and focused.
- • Afternoon meetings at 2-3 PM PDT (5-6 PM AST) work well for West Coast teams but may require Atlantic Canada staff to stay slightly late.
- • Atlantic Canada experiences early sunrise and sunset compared to Pacific regions. Plan outdoor business activities and events considering these differences.
- • The Halifax airport is a major hub for Atlantic Canada. If coordinating travel logistics, remember this gateway and plan layovers accordingly.
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