AST to COT
-1hAST
ASTSOURCECOT
COTGreen rows indicate typical business hours (9 AM - 5 PM)
AST and COT on the World Map
The map below highlights the AST (Atlantic Standard Time) and COT (Colombia 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.
COT – Colombia Time
UTC-05:00Colombia Time (COT) is the standard time for Colombia, 5 hours behind UTC.
- •Colombia does not observe daylight saving time.
- •COT is the same offset as EST (UTC-05:00).
- •Bogotá sits at 2,640m elevation, making it one of the highest capital cities.
Understanding the -1h Gap: AST vs COT
AST runs on Atlantic Standard Time (AST) at UTC-04:00. COT runs on Colombia Time (COT) at UTC-05:00. That puts AST 1 hour behind COT — a difference of -1h at the current offsets.
In practice, when it is 9:00 AM in AST it is 8:00 AM in COT. Midnight in AST is 11:00 PM in COT. Neither zone observes daylight saving time, so the offset between them stays constant all year.
AST to COT time conversion table
| AST (AST) | COT (COT) | Day |
|---|---|---|
| 12:00 AM | 11:00 PM | previous day |
| 6:00 AM | 5:00 AM | same day |
| 7:00 AM | 6:00 AM | same day |
| 8:00 AM | 7:00 AM | same day |
| 9:00 AM | 8:00 AM | same day |
| 12:00 PM | 11:00 AM | same day |
| 3:00 PM | 2:00 PM | same day |
| 5:00 PM | 4:00 PM | same day |
| 6:00 PM | 5:00 PM | same day |
| 9:00 PM | 8:00 PM | same day |
Why people convert AST to COT time
- Scheduling a call from AST to COT: a 10:00 AM start in AST lands at 9:00 AM in COT, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both AST and COT are inside the 9-to-5 working day between 10:00 AM and 5:00 PM AST time (9:00 AM–4:00 PM COT). That is roughly 7 hours of usable overlap.
- Coordinating a AST-based team with COT contacts: quoting times in the other side's local clock — not your own — removes the single biggest source of missed meetings.
- Always state the zone abbreviation, not just the hour. "3:00 PM AST" is unambiguous; "3 PM" across a -1h gap is not.
- Block 10:00 AM–5:00 PM AST as the recurring meeting window if you work primarily from AST and need COT colleagues present.
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 COT (Colombia Time)
Colombia Time (COT) is used throughout Colombia. Colombia does not observe daylight saving time. COT shares the same offset as EST (UTC-05:00). Bogotá, the capital, is one of the largest cities in South America.
Best time to call between AST and COT
Both AST and COT sit inside the 9 AM – 5 PM working day between 10:00 AM–5:00 PM AST, which is 9:00 AM–4:00 PM COT. That gives roughly 7 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
AST and COT share 7 hours of working-hours overlap (10:00 AM–5:00 PM AST), so scheduling a live meeting is straightforward.
AST is 1 hour behind COT (AST UTC-04:00 → COT UTC-05:00). The shared working window is 10:00 AM–5:00 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
COT
Does not observe DST
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 COT?
AST (AST, UTC-04:00) is 1 hour behind COT (COT, UTC-05:00). The gap is currently -1h.
How do I convert AST time to COT time?
Add -1h to AST local time. For example, 9:00 AM in AST is 8:00 AM in COT.
What time is it in COT right now?
COT uses COT at UTC-05:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -1h offset from AST.
What is the best time to call COT from AST?
Call between 10:00 AM and 5:00 PM AST — that maps to 9:00 AM–4:00 PM COT and keeps both parties inside the working day.
Which is behind, AST or COT?
AST is 1 hour behind COT. When it is 12:00 PM in AST it is 11:00 AM in COT.
Does daylight saving time affect the AST–COT difference?
Neither zone observes daylight saving time, so the -1h offset between AST and COT is fixed all year.
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 COT?
Not normally. The -1h gap only pushes the date over the previous day.
What is the time difference between AST and COT?
COT is -1h from AST.
What timezone is AST in?
AST operates on its local timezone.
What timezone is COT in?
COT operates on its local timezone.
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 COT timezone?
Major cities in the COT timezone include Bogotá, Medellín, Cali, Barranquilla, Cartagena.
What is the UTC offset for COT?
Colombia Time (COT) is at UTC-05:00.
What should I know about the COT timezone?
Colombia does not observe daylight saving time. COT is the same offset as EST (UTC-05:00).
When is it midnight in AST, what time is it in COT?
When it is 12:00 AM (midnight) in AST (AST), it is -1h later in COT (COT).
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See every conversion from AST →·See every conversion from COT →