Colorado Area Codes
| State: | Colorado (CO) |
| Area Codes: | 4 |
| Timezone: | Mountain (MDT) |
| Current Time: | 3:11 AM |
About Colorado Area Codes
Colorado (CO) uses 4 telephone area codes to serve its residents and businesses. With an estimated population of 7,734,597, Colorado is one of the smaller states in the North American Numbering Plan (NANP). The state is primarily in the Mountain Time Zone (MDT). The current local time in Colorado is 3:11 AM.
The largest cities in Colorado include Denver (pop. 2,876,625), Colorado Springs (pop. 642,413), Aurora (pop. 379,289), Fort Collins (pop. 312,666) and Lakewood (pop. 157,935) . Colorado has 64 counties spread across its territory. Each area code in CO covers a geographic region of the state, with some areas using overlay codes that share the same geographic territory as an existing area code.
When calling a Colorado phone number from outside the area code, you must dial the full 10-digit number: the 3-digit area code followed by the 7-digit local number. Many parts of Colorado now require 10-digit dialing even for local calls due to overlay area codes and the nationwide 988 Suicide & Crisis Lifeline implementation.
All Colorado Area Codes
The table below lists every active area code in Colorado, along with the major city served and other cities covered by each code.
| Area Code | Major City | Other Cities |
|---|---|---|
| 303 | Denver | Aurora, Fort Collins, Lakewood, Boulder, Arvada, Westminster, Centennial, Longmont and more |
| 719 | Denver | Colorado Springs, Lakewood, Pueblo, Fountain, Cañon City, Woodland Park, Alamosa, Trinidad and more |
| 720 | Denver | Aurora, Fort Collins, Lakewood, Boulder, Arvada, Westminster, Centennial, Longmont and more |
| 970 | Denver | Colorado Springs, Aurora, Fort Collins, Lakewood, Grand Junction, Greeley, Centennial, Loveland and more |
Largest Cities in Colorado
These are the largest cities in Colorado by population, along with their primary area codes and counties.
| City | Population | County |
|---|---|---|
| Denver | 2,876,625 | Denver County |
| Colorado Springs | 642,413 | El Paso County |
| Aurora | 379,289 | Adams County |
| Fort Collins | 312,666 | Larimer County |
| Lakewood | 157,935 | Jefferson County |
| Pueblo | 143,932 | Pueblo County |
| Thornton | 141,464 | Adams County |
| Grand Junction | 139,143 | Mesa County |
| Greeley | 137,810 | Weld County |
| Boulder | 124,345 | Boulder County |
Frequently Asked Questions
Colorado is primarily in the Mountain Time Zone (MDT).
The current local time is 3:11 AM.
The area code covering the most cities in Colorado is 970, which serves Denver and 122+ other communities.
Yes, most areas in Colorado now require 10-digit dialing (area code + 7-digit number) for all local calls. This requirement was implemented across the United States starting in October 2021 to support the 988 Suicide & Crisis Lifeline. Even if you are calling within the same area code, you need to dial all 10 digits.
To call a Colorado number from within the United States, dial the area code followed by the 7-digit phone number (e.g., 303-XXX-XXXX). From outside the US, dial your country's exit code, then 1 (the US country code), then the full 10-digit number.
Colorado has 64 counties.
The state's total estimated population is 7,734,597, spread across these counties and served by 4 area codes.
Denver is served by area code
303.
Colorado has 4 area codes in total — see the complete list above.
