West region · Mountain Time
Colorado Area Codes
All 6 area codes serving Colorado, the cities each one covers, and which are overlays. Colorado is served by 6 area codes in the Mountain Time zone.
Last updated October 3, 2026
Full list
Every Colorado area code
Colorado is served by 6 area codes in the Mountain Time zone. 3 of these are overlay codes layered over busy metros; the rest are geographic codes.
| Code | Area served | Type | In service |
|---|---|---|---|
| 303 | Denver, Boulder and the surrounding Front Range metro area in north-central Colorado | Geographic | Since 1947 |
| 719 | Southern and southeastern Colorado including Colorado Springs, Pueblo and the San Luis Valley | Geographic | Since 1988 |
| 720 | Denver, Boulder and the surrounding Front Range metro area in north-central Colorado | Overlay | Since 1998 |
| 748 | Northern and western Colorado including Fort Collins, Greeley, Grand Junction and the mountain resorts | Overlay | Since 2025 |
| 970 | Northern and western Colorado including Fort Collins, Greeley, Grand Junction and the mountain resorts | Geographic | Since 1995 |
| 983 | Denver, Boulder and the surrounding Front Range metro area in north-central Colorado | Overlay | Since 2022 |
Area codes and dialing in Colorado
Colorado's 6 area codes mix older geographic codes with newer overlays. The busiest metros — around Denver, Colorado Springs, Fort Collins — carry the most numbers and rely on overlays, which is why 10-digit dialing is required there. Quieter parts of the state may still use a single code. The oldest code in Colorado is 303 (Denver), one of the original 1947 area codes.
Whenever a Colorado region runs low on numbers, a new overlay is added on top rather than splitting the map, so existing customers keep their numbers. See 10-digit dialing for what that means in practice, or the newest area codes for upcoming changes.
Colorado city area code pages
Look up the area codes for a specific Colorado city: Denver · Fort Collins · Colorado Springs · Aurora · Boulder.
Browse Colorado another way
Explore by West region, by time zone, or jump to the city index. You can also see the complete numeric list of every US area code.
Quick answers
Colorado area code FAQ
How many area codes does Colorado have?
Colorado currently has 6 area codes: 303, 719, 720, 748, 970, 983.
What is the main area code for Colorado?
Colorado has no single main code. Its original 1947 area code was 303; today the main cities are served by 303 (Denver), 719 (Colorado Springs), 970 (Fort Collins), 720 (Denver), 983 (Denver).
Does Colorado require 10-digit dialing?
Yes, in its overlay areas you must dial all 10 digits, even for local calls. Dialing all 10 digits always works, so it is the safe habit.