Denver, CO Area Codes

Area codes serving Denver

Denver sits in Colorado, part of the West region and the Mountain Time zone. Its numbers are spread across an overlay of 3 codes that all cover the same ground: 303, 720, 983.

The original code is 303 (in service since 1947). As the area ran low on numbers, regulators added overlay codes on top instead of splitting the city, so longtime residents kept their numbers while new lines received a newer code.

Code	Area served	In service
303	Denver, Boulder and the surrounding Front Range metro area in north-central Colorado	January 1, 1947
720	Denver, Boulder and the surrounding Front Range metro area in north-central Colorado	June 1, 1998
983	Denver, Boulder and the surrounding Front Range metro area in north-central Colorado	June 17, 2022

Nearby cities sharing these area codes

• Aurora
• Lakewood
• Thornton
• Arvada
• Westminster
• Centennial
• Boulder
• Highlands Ranch
• Littleton
• Broomfield
• Longmont
• Castle Rock
• Parker
• Commerce City
• Brighton

How to pick an area code for a new number

When you activate a new line in Denver, the carrier assigns whichever code has numbers available — you usually can't choose. If a specific code matters to you (for example the prestige of 303), ask the carrier whether any blocks remain, or request a number transfer. All codes here dial identically and cost the same.

Dialing in Denver

Because Denver is an overlay area, 10-digit dialing is mandatory: always dial the area code plus the seven-digit number, even for a neighbor. See 10-digit dialing and overlay area codes for the background. For every code in Colorado, visit the Colorado area codes page.