Chicago to AST

Chicago vs AST: Offsets, DST and Best Call Times

Chicago runs on Central Daylight Time (CDT) at UTC-05:00, currently observing daylight saving time. AST runs on Atlantic Standard Time (AST) at UTC-04:00. That puts Chicago 1 hour ahead of AST — a difference of +1h at the current offsets.

In practice, when it is 9:00 AM in Chicago it is 10:00 AM in AST. Midnight in Chicago is 1:00 AM in AST.Chicago observes daylight saving time while AST does not, so the gap narrows or widens by an hour part of the year.

Chicago to AST time conversion table

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.

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 Chicago and AST

Both Chicago and AST sit inside the 9 AM – 5 PM working day between 9:00 AM–4:00 PM CDT, 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

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