312 Area Code
Chicago (city core), Illinois
Area code 312 is located in Chicago (city core), Illinois. It covers Chicago (downtown), The Loop, and surrounding areas in the Central time zone (UTC-6). Administered by NANPA.
Where is area code 312?
Area code 312 is located in Chicago (city core), Illinois. It covers Chicago (downtown), The Loop, and surrounding areas in the Central time zone (UTC-6).
Area code 312 is overlaid by area code 872. Both codes serve the same geographic region and require 10-digit dialing for local calls.
Cities Covered by Area Code 312
Area code 312 primarily serves the Chicago (city core) area of Illinois. The exact coverage includes Chicago (downtown), The Loop, and Near North Side, along with surrounding communities and suburbs.
Time Zone
Central Time — UTC-6
Area code 312 operates in the Central Time Zone. When calling 312 numbers from a different time zone, be sure to account for the time difference to reach people during business hours.
About Area Code 312
Area code 312 was introduced in 1947 as a geographic area code serving Chicago (city core), Illinois. As demand for phone numbers grew, overlay code 872 was added to the same region, requiring 10-digit dialing for local calls. Area codes are administered by NANPA (North American Numbering Plan Administration), the organization responsible for managing phone number resources in the US and Canada.