AST to BST Converter
Convert time between Atlantic Standard Time (AST) and British Summer Time (BST)
Atlantic Standard Time (AST)
British Summer Time (BST)
Time Difference
British Summer Time (BST) is 0 hours ahead of Atlantic Standard Time (AST)
Select Date
Select Time
Quick Reference
| AST | BST |
|---|---|
| 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 |
| 18:00 | 22:00 |
| 20:00 | 00:00 |
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 BST Time Conversion
Converting time between Atlantic Standard Time (AST) and British Summer Time (BST) is essential for coordinating between Atlantic Canada and the United Kingdom. AST is UTC-4 (the standard time in Atlantic Canada, used November to March), while BST is UTC+1 (the summer time in the UK, used March to November). AST is 5 hours behind BST, making it one of the significant transatlantic timezone differences.
This conversion is particularly relevant for businesses, educational institutions, and cultural organizations with strong Atlantic Canada-UK ties. The timing of daylight saving transitions differs between the two regions - Atlantic Canada and the US switch on the second Sunday in March, while the UK switches on the last Sunday in March. This creates a brief one-week period in late March where the offset is only 4 hours. During winter months (November to March), the UK operates on GMT (UTC+0) and Atlantic Canada on AST (UTC-4), maintaining a 4-hour difference. Understanding these variations is crucial for seamless transatlantic coordination.
Common Use Cases for AST to BST Conversion
Business & Work
- Scheduling meetings between Atlantic Canada and UK office locations
- Coordinating finance and banking operations across the Atlantic
- Managing technology partnerships between Atlantic and UK companies
- Planning conference calls for international business coordination
Personal & Travel
- Planning travel from Atlantic Canada to the United Kingdom
- Coordinating with family and friends in the UK
- Scheduling international educational exchange programs
- Arranging virtual meetings with UK-based colleagues and collaborators
Time Zone Information
Atlantic Standard Time (AST)
- UTC Offset: UTC-4 (UTC-3 during ADT)
- IANA Timezone: America/Halifax
- Daylight Saving: Transitions to ADT (UTC-3) on second Sunday in March
- Major Cities: Halifax, Saint John, Charlottetown, Fredericton
- Coverage: Atlantic Canada (Nova Scotia, New Brunswick, Prince Edward Island)
British Summer Time (BST)
- UTC Offset: UTC+1 (UTC+0 during GMT in winter)
- IANA Timezone: Europe/London
- Daylight Saving: Transitions from GMT to BST on last Sunday in March
- Major Cities: London, Edinburgh, Manchester, Birmingham
- Coverage: United Kingdom
Quick Reference: AST to BST
Remember: BST is 5 hours ahead of AST (spring-fall). In winter, the UK is on GMT (UTC+0) and Atlantic Canada on AST (UTC-4), creating a 4-hour difference. The UK transitions to BST on a different date than Atlantic Canada, creating a brief coordination challenge in late March.
Frequently Asked Questions
What is the time difference between AST and BST?
Atlantic Standard Time (AST) is UTC-4, while British Summer Time (BST) is UTC+1. This creates a 5-hour time difference, with the UK being ahead of Atlantic Canada. When it's 12:00 PM (noon) in Halifax (AST), it's 5:00 PM in London (BST). This significant offset reflects the geographic distance and time zone positions across the Atlantic Ocean.
How does daylight saving time affect AST to BST conversion?
Atlantic Canada transitions to Atlantic Daylight Time (ADT, UTC-3) in spring, while the UK observes British Summer Time (BST, UTC+1) during the same period. Interestingly, both regions transition on different dates. The US (and Atlantic Canada) switch on the second Sunday in March, while the UK switches on the last Sunday in March. This timing difference creates a brief period where the offset changes by an hour. Outside of daylight saving (November to March), the UK is on GMT (UTC+0) and Atlantic Canada is on AST (UTC-4), creating a 4-hour difference.
When is AST to BST conversion most relevant?
The AST-BST conversion is relevant from late March through early November when both regions observe daylight time. This is the prime coordination period for Atlantic Canada-UK business relationships, including finance, tech, education, and culture sectors. The 5-hour time difference requires careful scheduling, with morning meetings in Halifax aligning with late afternoon in London. Many UK-Atlantic Canada partnerships schedule during this period to maximize business hour overlap.
What are the best times to schedule calls between Atlantic Canada and the UK?
Due to the 4-5 hour difference, scheduling requires strategic planning. Late morning in Halifax (10 AM-12 PM AST/ADT) aligns with late afternoon/early evening in London (3-5 PM GMT/BST), making this an ideal window for business coordination. Alternatively, late afternoon Halifax time (3-5 PM AST/ADT) reaches early morning next day London time (7-9 AM GMT/BST). For recurring meetings, the late morning/early afternoon Halifax window is typically the most practical for both regions.
How do the different DST transition dates affect scheduling?
Atlantic Canada and the UK transition to daylight time on different dates, creating a brief coordination challenge. From mid-March to late March, Atlantic Canada is on ADT (UTC-3) while the UK is still on GMT (UTC+0), creating a 3-hour difference. After the UK transitions to BST (UTC+1) in late March, the offset becomes 4 hours (ADT to BST). This week-long variation requires awareness when scheduling critical meetings during late March. Documenting time zones explicitly is crucial during these transition windows.
Why is Atlantic-UK coordination significant?
Atlantic Canada and the UK share strong economic, cultural, and historical ties. The region benefits from significant UK investment in energy, finance, and technology sectors. The UK is a major source of tourism to Atlantic Canada and vice versa. Educational institutions maintain robust exchange programs. The 4-5 hour time difference is manageable compared to other transatlantic timezone pairs and makes Atlantic Canada an attractive hub for UK businesses seeking North American operations. Understanding the timezone relationship is essential for these cross-Atlantic partnerships.
Pro Tips
- • AST to BST creates a 5-hour time difference (spring-fall, when both are observing daylight time). In winter, it's 4 hours (AST to GMT).
- • Late morning Halifax calls (10 AM-12 PM) reach London late afternoon (3-5 PM). This is the prime window for transatlantic business coordination.
- • Remember the UK transition date: The UK switches to BST on the last Sunday in March, one week after Atlantic Canada switches to ADT. Plan accordingly.
- • For recurring transatlantic meetings, the late morning Halifax window works best - it's mid-afternoon in London, still within business hours.
- • Use explicit timezone notation (AST, ADT, GMT, BST) in all meeting invitations. The significant offset increases the risk of scheduling errors.
- • Atlantic Canada-UK coordination is ideal for finance, tech, and education sectors. Both regions' business hours create strong overlap during the late morning/early afternoon window.
Update Logs
View the latest updates and features