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COT to AST

+1h

COT

COTSOURCE
UTC-05:00
HH12
:
MM00
  
12:00 (24-hr)
12 AM6 AM12 PM6 PM12 AM

AST

AST
UTC-03:00☀ DST active
HH01
:
MM00
  
13:00 (24-hr)
12 AM6 AM12 PM6 PM12 AM
COT
AST
12:00 AM
2:00 AM
2:00 AM
4:00 AM
4:00 AM
6:00 AM
6:00 AM
8:00 AM
8:00 AM
10:00 AM
10:00 AM
12:00 PM
12:00 PM
2:00 PM
2:00 PM
4:00 PM
4:00 PM
6:00 PM
6:00 PM
8:00 PM
8:00 PM
10:00 PM
10:00 PM
12:00 AM+1

Green rows indicate typical business hours (9 AM - 5 PM)

COT and AST on the World Map

The map below highlights the COT (Colombia Time) and AST (Atlantic Standard Time) timezone regions across the globe.

COTASTBogotáMedellínCaliBarranquillaHalifaxSan JuanSanto DomingoCaracas
COT Zone
→
AST Zone

Explore all world timezones interactively →

COT – Colombia Time

UTC-05:00

Colombia Time (COT) is the standard time for Colombia, 5 hours behind UTC.

Countries in COT
Colombia
Major Cities in COT
BogotáMedellínCaliBarranquillaCartagena
Key Facts about COT
  • •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.
Daylight Saving:No – UTC-05:00 year-round
Learn more about COT on Wikipedia

AST – Atlantic Standard Time

UTC-04:00

Atlantic Standard Time (AST) is the time zone for the Canadian Atlantic provinces and the Caribbean, 4 hours behind UTC.

Countries in AST
Canada (Atlantic provinces)Puerto RicoUS Virgin IslandsDominican RepublicVenezuelaBoliviaBarbadosTrinidad and Tobago
Major Cities in AST
HalifaxSan JuanSanto DomingoCaracasLa PazFrederictonCharlottetown
Key Facts about AST
  • •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.
Daylight Saving:Yes – switches to ADT
Learn more about AST on Wikipedia

Understanding the +1h Gap: COT vs AST

COT runs on Colombia Time (COT) at UTC-05:00. AST runs on Atlantic Standard Time (AST) at UTC-04:00. That puts COT 1 hour ahead of AST — a difference of +1h at the current offsets.

In practice, when it is 9:00 AM in COT it is 10:00 AM in AST. Midnight in COT is 1:00 AM in AST. Neither zone observes daylight saving time, so the offset between them stays constant all year.

COT to AST time conversion table

COT (COT)AST (AST)Day
12:00 AM1:00 AMsame day
6:00 AM7:00 AMsame day
7:00 AM8:00 AMsame day
8:00 AM9:00 AMsame day
9:00 AM10:00 AMsame day
12:00 PM1:00 PMsame day
3:00 PM4:00 PMsame day
5:00 PM6:00 PMsame day
6:00 PM7:00 PMsame day
9:00 PM10:00 PMsame day

Why people convert COT to AST time

  • Scheduling a call from COT to AST: a 10:00 AM start in COT lands at 11:00 AM in AST, so you can confirm the slot without doing the arithmetic yourself.
  • Finding shared working hours: both COT and AST are inside the 9-to-5 working day between 9:00 AM and 4:00 PM COT time (10:00 AM–5:00 PM AST). That is roughly 7 hours of usable overlap.
  • Booking travel or deliveries: tracking AST local time against COT keeps pickup windows and arrival estimates honest across the +1h offset.
  • Always state the zone abbreviation, not just the hour. "3:00 PM COT" is unambiguous; "3 PM" across a +1h gap is not.
  • Block 9:00 AM–4:00 PM COT as the recurring meeting window if you work primarily from COT and need AST colleagues present.

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.

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 COT and AST

Both COT and AST sit inside the 9 AM – 5 PM working day between 9:00 AM–4:00 PM COT, which is 10:00 AM–5:00 PM AST. That gives roughly 7 hours of shared time — the safest window for a live call or meeting.

Business hours overlap

COT and AST share 7 hours of working-hours overlap (9:00 AM–4:00 PM COT), so scheduling a live meeting is straightforward.

COT is 1 hour ahead of AST (COT UTC-05:00 → AST UTC-04:00). The shared working window is 9:00 AM–4:00 PM COT. Remember to re-check around daylight-saving transitions.

🕐 Daylight Saving Time Info

COT

Does not observe DST

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:

⏳
History of Timekeeping
From sundials to atomic clocks - 5000 years of measuring time
🌍
How Time Zones Work
UTC, offsets, and why zones don't follow straight lines
☀️
Daylight Saving Time
DST dates, which countries observe it, and the ongoing debate

Frequently Asked Questions

What is the time difference between COT and AST?

COT (COT, UTC-05:00) is 1 hour ahead of AST (AST, UTC-04:00). The gap is currently +1h.

How do I convert COT time to AST time?

Add +1h to COT local time. For example, 9:00 AM in COT is 10:00 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 +1h offset from COT.

What is the best time to call AST from COT?

Call between 9:00 AM and 4:00 PM COT — that maps to 10:00 AM–5:00 PM AST and keeps both parties inside the working day.

Which is ahead, COT or AST?

COT is 1 hour ahead of AST. When it is 12:00 PM in COT it is 1:00 PM in AST.

Does daylight saving time affect the COT–AST difference?

Neither zone observes daylight saving time, so the +1h offset between COT and AST is fixed all year.

Which other cities share COT's time zone?

COT also covers Bogotá, Medellín, Cali, Barranquilla, Cartagena.

Which countries use COT, COT's zone?

COT is used in Colombia.

Is there a day difference between COT and AST?

Not normally. The +1h gap only pushes the date over for late-evening times.

What is the time difference between COT and AST?

AST is +1h from COT.

What timezone is COT in?

COT operates on its local timezone.

What timezone is AST in?

AST operates on its local timezone.

Which countries use COT (Colombia Time)?

COT is used in Colombia.

Does COT observe daylight saving time?

No, COT does not observe daylight saving time and remains at UTC-05:00 year-round.

What are some interesting facts about COT?

Colombia does not observe daylight saving time. COT is the same offset as EST (UTC-05:00).

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 COT, what time is it in AST?

When it is 12:00 AM (midnight) in COT (COT), it is +1h later in AST (AST).

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