AST to London
+5hAST
ASTSOURCELondon
BSTGreen rows indicate typical business hours (9 AM - 5 PM)
AST and BST on the World Map
The map below highlights the AST (Atlantic Standard Time) and BST (Greenwich Mean Time) timezone regions across the globe.
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.
GMT – Greenwich Mean Time
UTC+00:00Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London. It is the same as UTC+00:00.
- •GMT is based on the Prime Meridian (0° longitude) passing through Greenwich, London.
- •The Royal Observatory in Greenwich has been the reference point for GMT since 1884.
- •GMT and UTC are often used interchangeably, but UTC is based on atomic clocks.
- •Iceland uses GMT year-round and never observes daylight saving time.
- •The UK switches from GMT to BST (British Summer Time) in late March each year.
About London
WikipediaLondon, where Greenwich Mean Time (GMT) originates, is the world's leading financial center alongside New York. The city bridges European and American business hours.
Big Ben is actually the name of the bell inside the Elizabeth Tower, not the tower itself.
AST vs London: Offsets, DST and Best Call Times
AST runs on Atlantic Standard Time (AST) at UTC-04:00. London runs on British Summer Time (BST) at UTC+01:00, also currently on daylight saving time. That puts AST 5 hours ahead of London — a difference of +5h at the current offsets.
In practice, when it is 9:00 AM in AST it is 2:00 PM in London. Midnight in AST is 5:00 AM in London.London observes daylight saving time while AST does not, so the gap narrows or widens by an hour part of the year.
AST to London time conversion table
| AST (AST) | London (BST) | Day |
|---|---|---|
| 12:00 AM | 5:00 AM | same day |
| 6:00 AM | 11:00 AM | same day |
| 7:00 AM | 12:00 PM | same day |
| 8:00 AM | 1:00 PM | same day |
| 9:00 AM | 2:00 PM | same day |
| 12:00 PM | 5:00 PM | same day |
| 3:00 PM | 8:00 PM | same day |
| 5:00 PM | 10:00 PM | same day |
| 6:00 PM | 11:00 PM | same day |
| 9:00 PM | 2:00 AM | next day |
Why people convert AST to London time
- Scheduling a call from AST to London: a 10:00 AM start in AST lands at 3:00 PM in London, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both AST and London are inside the 9-to-5 working day between 9:00 AM and 12:00 PM AST time (2:00 PM–5:00 PM BST). That is roughly 3 hours of usable overlap.
- Watching a live event or market open: AST viewers need 2:00 PM in London to catch a 9:00 AM start there, and 7:00 PM if the event is anchored to AST.
- Always state the zone abbreviation, not just the hour. "3:00 PM AST" is unambiguous; "3 PM" across a +5h gap is not.
- Block 9:00 AM–12:00 PM AST as the recurring meeting window if you work primarily from AST and need London colleagues present.
- London: Clocks fall back on Sun, Oct 25, 2026. Any meeting series spanning that date will shift by an hour in local time.
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.
About GMT (Greenwich Mean Time)
Greenwich Mean Time (GMT) is the clock time at the Royal Observatory in Greenwich, London, which sits on the Prime Meridian (0° longitude). GMT serves as the reference point from which all other time zones are calculated. The United Kingdom uses GMT during winter months and switches to British Summer Time (BST, UTC+01:00) from late March to late October. Several West African nations use GMT year-round. GMT is often used interchangeably with UTC (Coordinated Universal Time), although technically they are different – UTC is based on atomic clocks while GMT is based on Earth's rotation.
Best time to call between AST and London
Both AST and London sit inside the 9 AM – 5 PM working day between 9:00 AM–12:00 PM AST, which is 2:00 PM–5:00 PM BST. That gives roughly 3 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
AST and London overlap for about 3 hours during the working day — enough for meetings if you avoid the edges of the window.
AST is 5 hours ahead of London (AST UTC-04:00 → BST UTC+01:00). The shared working window is 9:00 AM–12:00 PM AST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
AST
☀ Currently in DST
Standard: UTC-04:00 · DST: UTC-03:00
Clocks fall back on Sun, Nov 1, 2026
London
☀ Currently in DST
Standard: UTC+00:00 · DST: UTC+01:00
Clocks fall back on Sun, Oct 25, 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 AST and London?
AST (AST, UTC-04:00) is 5 hours ahead of London (BST, UTC+01:00). The gap is currently +5h.
How do I convert AST time to London time?
Add +5h to AST local time. For example, 9:00 AM in AST is 2:00 PM in London.
What time is it in London right now?
London uses BST at UTC+01:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +5h offset from AST.
What is the best time to call London from AST?
Call between 9:00 AM and 12:00 PM AST — that maps to 2:00 PM–5:00 PM BST and keeps both parties inside the working day.
Which is ahead, AST or London?
AST is 5 hours ahead of London. When it is 12:00 PM in AST it is 5:00 PM in London.
Do AST and London use different time zones?
AST uses AST at UTC-04:00, while London (UK) uses BST at UTC+01:00. The IANA identifiers are America/Halifax and Europe/London.
Does daylight saving time affect the AST–London difference?
Yes at the moment: London is on daylight saving time and AST is not, so the +5h gap shifts by an hour when exactly one of them changes clocks.
Which other cities share AST's time zone?
AST also covers Halifax, San Juan, Santo Domingo, Caracas, La Paz, Fredericton, Charlottetown.
Which countries use AST, AST's zone?
AST is used in Canada (Atlantic provinces), Puerto Rico, US Virgin Islands, Dominican Republic, Venezuela, Bolivia, Barbados, Trinidad and Tobago.
Is there a day difference between AST and London?
Not normally. The +5h gap only pushes the date over for late-evening times.
What is the time difference between AST and London?
London is +5h from AST.
What timezone is AST in?
AST operates on its local timezone.
What timezone is London in?
London, where Greenwich Mean Time (GMT) originates, is the world's leading financial center alongside New York. The city bridges European and American business hours.
What are the business hours in London?
Standard business hours in London are 9:00 AM - 5:00 PM GMT.
Which countries use AST (Atlantic Standard Time)?
AST is used in Canada (Atlantic provinces), Puerto Rico, US Virgin Islands, Dominican Republic, Venezuela, Bolivia, and 2 more countries.
Does AST observe daylight saving time?
Yes, AST switches to ADT during summer months.
What are some interesting facts about AST?
Puerto Rico uses AST year-round and does not observe DST. AST is 1 hour ahead of EST.
Which cities are in the GMT timezone?
Major cities in the GMT timezone include London, Dublin, Lisbon, Accra, Reykjavik, Edinburgh, Casablanca, Dakar.
What is the UTC offset for GMT?
Greenwich Mean Time (GMT) is at UTC+00:00. During daylight saving time, it shifts to BST.
What should I know about the GMT timezone?
GMT is based on the Prime Meridian (0° longitude) passing through Greenwich, London. The Royal Observatory in Greenwich has been the reference point for GMT since 1884.
When is it midnight in AST, what time is it in London?
When it is 12:00 AM (midnight) in AST (AST), it is +5h later in London (GMT).
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