AST to Chicago
-1hAST
ASTSOURCEChicago
CDTGreen rows indicate typical business hours (9 AM - 5 PM)
AST and CDT on the World Map
The map below highlights the AST (Atlantic Standard Time) and CDT (Central Standard 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.
CST – Central Standard Time
UTC-06:00Central Standard Time (CST) is the time zone for the central United States, Canada, and Mexico, 6 hours behind UTC.
- •CST covers 20 US states fully or partially.
- •Chicago and Houston are the two largest cities in the Central Time Zone.
- •Mexico City, one of the world's most populous cities, operates on CST.
- •CST is 1 hour behind EST and 2 hours ahead of PST.
About Chicago
WikipediaChicago operates on Central Time (CST/CDT), 1 hour behind New York. Home to CME and CBOE, Chicago is a global center for derivatives trading.
The Chicago Board of Trade is the world's oldest futures and options exchange.
Time Conversion Guide: AST to Chicago
AST runs on Atlantic Standard Time (AST) at UTC-04:00. Chicago runs on Central Daylight Time (CDT) at UTC-05:00, also currently on daylight saving time. That puts AST 1 hour behind Chicago — a difference of -1h at the current offsets.
In practice, when it is 9:00 AM in AST it is 8:00 AM in Chicago. Midnight in AST is 11:00 PM in Chicago.Chicago observes daylight saving time while AST does not, so the gap narrows or widens by an hour part of the year.
AST to Chicago time conversion table
| AST (AST) | Chicago (CDT) | 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 Chicago time
- Scheduling a call from AST to Chicago: a 10:00 AM start in AST lands at 9:00 AM in Chicago, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both AST and Chicago are inside the 9-to-5 working day between 10:00 AM and 5:00 PM AST time (9:00 AM–4:00 PM CDT). That is roughly 7 hours of usable overlap.
- Watching a live event or market open: AST viewers need 8:00 AM in Chicago to catch a 9:00 AM start there, and 1:00 AM 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 -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 Chicago colleagues present.
- Chicago: Clocks fall back on Sun, Nov 1, 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 CST (Central Standard Time)
Central Standard Time (CST) covers the central region of North America. It is the second most populous time zone in the US, including major cities like Chicago, Houston, and Dallas. CST is also used in Mexico City and much of Central America including Guatemala, Honduras, El Salvador, and Costa Rica. During summer, most of the US and Canada switch to Central Daylight Time (CDT, UTC-05:00), while Mexico and Central American countries generally remain on CST.
Best time to call between AST and Chicago
Both AST and Chicago 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 CDT. That gives roughly 7 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
AST and Chicago 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 Chicago (AST UTC-04:00 → CDT 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
Chicago
☀ Currently in DST
Standard: UTC-06:00 · DST: UTC-05:00
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 AST and Chicago?
AST (AST, UTC-04:00) is 1 hour behind Chicago (CDT, UTC-05:00). The gap is currently -1h.
How do I convert AST time to Chicago time?
Add -1h to AST local time. For example, 9:00 AM in AST is 8:00 AM in Chicago.
What time is it in Chicago right now?
Chicago uses CDT 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 Chicago from AST?
Call between 10:00 AM and 5:00 PM AST — that maps to 9:00 AM–4:00 PM CDT and keeps both parties inside the working day.
Which is behind, AST or Chicago?
AST is 1 hour behind Chicago. When it is 12:00 PM in AST it is 11:00 AM in Chicago.
Do AST and Chicago use different time zones?
AST uses AST at UTC-04:00, while Chicago (USA) uses CDT at UTC-05:00. The IANA identifiers are America/Halifax and America/Chicago.
Does daylight saving time affect the AST–Chicago difference?
Yes at the moment: Chicago is on daylight saving time and AST is not, so the -1h 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 Chicago?
Not normally. The -1h gap only pushes the date over the previous day.
What is the time difference between AST and Chicago?
Chicago is -1h from AST.
What timezone is AST in?
AST operates on its local timezone.
What timezone is Chicago in?
Chicago operates on Central Time (CST/CDT), 1 hour behind New York. Home to CME and CBOE, Chicago is a global center for derivatives trading.
What are the business hours in Chicago?
Standard business hours in Chicago are 8:00 AM - 5:00 PM CST.
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 CST timezone?
Major cities in the CST timezone include Chicago, Houston, Dallas, San Antonio, Mexico City, Austin, Winnipeg, Memphis.
What is the UTC offset for CST?
Central Standard Time (CST) is at UTC-06:00. During daylight saving time, it shifts to CDT.
What should I know about the CST timezone?
CST covers 20 US states fully or partially. Chicago and Houston are the two largest cities in the Central Time Zone.
When is it midnight in AST, what time is it in Chicago?
When it is 12:00 AM (midnight) in AST (AST), it is -1h later in Chicago (CST).
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