Dublin to AST
-5hDublin
ISTSOURCEAST
ASTGreen rows indicate typical business hours (9 AM - 5 PM)
IST and AST on the World Map
The map below highlights the IST (Greenwich Mean Time) and AST (Atlantic Standard Time) timezone regions across the globe.
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.
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.
Understanding the -5h Gap: Dublin vs AST
Dublin runs on Irish Standard Time (IST) at UTC+01:00, currently observing daylight saving time. AST runs on Atlantic Standard Time (AST) at UTC-04:00. That puts Dublin 5 hours behind AST — a difference of -5h at the current offsets.
In practice, when it is 9:00 AM in Dublin it is 4:00 AM in AST. Midnight in Dublin is 7:00 PM in AST.Dublin observes daylight saving time while AST does not, so the gap narrows or widens by an hour part of the year.
Dublin to AST time conversion table
| Dublin (IST) | AST (AST) | Day |
|---|---|---|
| 12:00 AM | 7:00 PM | previous day |
| 6:00 AM | 1:00 AM | same day |
| 7:00 AM | 2:00 AM | same day |
| 8:00 AM | 3:00 AM | same day |
| 9:00 AM | 4:00 AM | same day |
| 12:00 PM | 7:00 AM | same day |
| 3:00 PM | 10:00 AM | same day |
| 5:00 PM | 12:00 PM | same day |
| 6:00 PM | 1:00 PM | same day |
| 9:00 PM | 4:00 PM | same day |
Why people convert Dublin to AST time
- Scheduling a call from Dublin to AST: a 10:00 AM start in Dublin lands at 5:00 AM in AST, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both Dublin and AST are inside the 9-to-5 working day between 2:00 PM and 5:00 PM IST time (9:00 AM–12:00 PM AST). That is roughly 3 hours of usable overlap.
- Booking travel or deliveries: tracking AST local time against Dublin keeps pickup windows and arrival estimates honest across the -5h offset.
- Always state the zone abbreviation, not just the hour. "3:00 PM IST" is unambiguous; "3 PM" across a -5h gap is not.
- Block 2:00 PM–5:00 PM IST as the recurring meeting window if you work primarily from Dublin and need AST colleagues present.
- Dublin: Clocks fall back on Sun, Oct 25, 2026. Re-check this page after that date because the offset changes and so does the -5h gap.
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.
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.
Best time to call between Dublin and AST
Both Dublin and AST sit inside the 9 AM – 5 PM working day between 2:00 PM–5:00 PM IST, which is 9:00 AM–12:00 PM AST. That gives roughly 3 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
Dublin and AST overlap for about 3 hours during the working day — enough for meetings if you avoid the edges of the window.
Dublin is 5 hours behind AST (IST UTC+01:00 → AST UTC-04:00). The shared working window is 2:00 PM–5:00 PM IST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
Dublin
☀ Currently in DST
Standard: UTC+00:00 · DST: UTC+01:00
Clocks fall back on Sun, Oct 25, 2026
AST
☀ Currently in DST
Standard: UTC-04:00 · DST: UTC-03:00
Clocks fall back on Sun, Nov 1, 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 Dublin and AST?
Dublin (IST, UTC+01:00) is 5 hours behind AST (AST, UTC-04:00). The gap is currently -5h.
How do I convert Dublin time to AST time?
Add -5h to Dublin local time. For example, 9:00 AM in Dublin is 4:00 AM in AST.
What time is it in AST right now?
AST uses AST at UTC-04:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -5h offset from Dublin.
What is the best time to call AST from Dublin?
Call between 2:00 PM and 5:00 PM IST — that maps to 9:00 AM–12:00 PM AST and keeps both parties inside the working day.
Which is behind, Dublin or AST?
Dublin is 5 hours behind AST. When it is 12:00 PM in Dublin it is 7:00 AM in AST.
Do Dublin and AST use different time zones?
Dublin (Ireland) uses IST at UTC+01:00, while AST uses AST at UTC-04:00. The IANA identifiers are Europe/Dublin and America/Halifax.
Does daylight saving time affect the Dublin–AST difference?
Yes at the moment: Dublin 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 Dublin's time zone?
IST also covers London, Dublin, Lisbon, Accra, Reykjavik, Edinburgh, Casablanca, Dakar and 5 more.
Which countries use IST, Dublin's zone?
IST is used in United Kingdom, Ireland, Iceland, Portugal (mainland), Ghana, Senegal, Mali, Mauritania and 7 more.
Is there a day difference between Dublin and AST?
Not normally. The -5h gap only pushes the date over the previous day.
What is the time difference between Dublin and AST?
AST is -5h from Dublin.
What timezone is Dublin in?
Dublin operates on its local timezone.
What timezone is AST in?
AST operates on its local timezone.
Which countries use GMT (Greenwich Mean Time)?
GMT is used in United Kingdom, Ireland, Iceland, Portugal (mainland), Ghana, Senegal, and 9 more countries.
Does GMT observe daylight saving time?
Yes, GMT switches to BST during summer months.
What are some interesting facts about GMT?
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.
Which cities are in the AST timezone?
Major cities in the AST timezone include Halifax, San Juan, Santo Domingo, Caracas, La Paz, Fredericton, Charlottetown.
What is the UTC offset for AST?
Atlantic Standard Time (AST) is at UTC-04:00. During daylight saving time, it shifts to ADT.
What should I know about the AST timezone?
Puerto Rico uses AST year-round and does not observe DST. AST is 1 hour ahead of EST.
When is it midnight in Dublin, what time is it in AST?
When it is 12:00 AM (midnight) in Dublin (GMT), it is -5h later in AST (AST).
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