Thornton, Colorado Area Code

Thornton, CO Area Codes are

303 and 720

Thornton, CO utilizes an area code overlay in which area codes 303 and 720 serve the same geographic area. Ten digit dialing (area code + seven digit number) is necessary.

In addition to Thornton, CO area code information read more about area codes 303 and 720 details and Colorado area codes.

Thornton, CO is located in Broomfield County and observes the Mountain Time Zone. View our Times by Area Code tool.

Colorado Area Code Map