COLORADO · AREA CODE GUIDE
303 area code location: Denver and Longmont, Colorado
- Local date and time
- Mountain Time
Map data: HSIP (2010) · NANPA · US Census Bureau, checked 26 September 2026. Boundaries are approximate.
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Download the 303 area code map
A printable area code 303 location map, with time zone and state. Use the PNG image in a document or slide; the SVG stays sharp at any size.
303 area code at a glance
- State
- Colorado
- Primary cities
- Denver, Longmont, and Fort Lupton
- Established
- Population
- Largest community: Denver, 740,613 (2025)Not an area-code population.
- Prefixes in service
- 784 as of 13 October 2026
An area code does not show where a caller is now.
History
Country and calling code: United States (+1).
New code planned: No, as of 22 September 2026.
Time zone
- Mountain Time
- Standard time UTC−07:00
- Daylight saving time UTC−06:00
Counties and cities covered
303 numbers are issued across 13 communities. These are telephone exchange areas, which follow the phone network rather than city limits, so a place can sit just outside the boundary of the town it is named for.
Counties of the communities we could place (the code may reach further): Weld County, Arapahoe County, Adams County, Boulder County, Clear Creek County, and Denver County.
- Denver
- Longmont
- Fort Lupton
- Bennett
- Keenesburg
- Deer Trail
- Hudson
- Georgetown
- Allenspark-Lyons
- Byers
- Deckers
- Roggen
- Strasburg
Notable places in 303
| Place | Where | What it is |
|---|---|---|
| Denver International Airport | 21.0 km from Denver | Commercial airport, 40,012,895 enplanements (2024) |
| University of Colorado Boulder | 22.9 km from Longmont | University, 46,985 12-month enrollment (2023–24) |
| Ball Arena | 10.9 km from Denver | Arena |
| University of Denver | 11.6 km from Denver | University, 16,004 12-month enrollment (2023–24) |
| Empower Field at Mile High | 12.0 km from Denver | Stadium |
| Denver Art Museum | 9.7 km from Denver | Museum |
| Coors Field | 9.7 km from Denver | Stadium |
| University of Colorado Denver | 10.6 km from Denver | University, 29,066 12-month enrollment (2023–24) |
| Buckley Space Force Base | 12.9 km from Denver | US Air Force installation |
| Centennial Airport | 21.5 km from Denver | Airport |
Also serving this area
Questions about 303
Where is the 303 area code?
303 is in Colorado. Its numbers are issued in Denver, Longmont, Fort Lupton, and 10 other communities.
What time zone is area code 303 in?
303 is in Mountain Time. Daylight saving time is observed.
Does 303 have an overlay?
Yes. 720 was added as an overlay on 303 on 1 June 1998. 983 was added as an overlay on 303 on 17 June 2022.
What cities are in the 303 area code?
Denver, Longmont, Fort Lupton, Bennett, and Keenesburg, and 8 other communities.
What state is area code 303 in?
Area code 303 is in Colorado.
What counties are covered by area code 303?
Area code 303 covers communities in Weld County, Arapahoe County, Adams County, Boulder County, Clear Creek County, and Denver County.
Is 303 a toll-free area code?
No. 303 is a geographic area code. The toll-free codes are 800, 833, 844, 855, 866, 877, and 888.
Sources: NANPA area code listing, NANPA places by area code, NANPA central office code assignments, U.S. Census Bureau population estimates, OMB metropolitan area delineations. Checked .
Business phone numbers in area code 303, answered by an AI agent
A local number for Denver, Longmont, and Fort Lupton, Colorado, with an AI receptionist that takes caller details, answers the questions you give it, and books appointments. Numbers depend on what carriers have left.