Area Code 303: Denver, Colorado
303 is a telephone area code serving Colorado, including Denver. It is part of the North American Numbering Plan and is dialed with the country code +1.
Numbers beginning with 303 are located in Colorado, United States (NANP region: Denver Metro). The code covers Denver.
How to Dial Area Code 303
| Calling from | What to dial |
|---|---|
| Anywhere in the US or Canada | 1 303 XXX-XXXX (10-digit dialing: 303 + 7-digit number) |
| Local call inside the same area code | 7-digit number in most areas; 10 digits where an overlay code is active |
| From the UK or Europe | 00 1 303 XXX XXXX |
| From Australia | 0011 1 303 XXX XXXX |
| From a mobile phone anywhere | +1 303 XXX XXXX |
Whatever country you are calling from, the + symbol replaces the exit code. Save the contact as +1 303 XXXXXXX and it will dial correctly from any phone in the world.
Time Zone for Area Code 303
Calls to a 303 number ring in the America/Denver time zone, standard offset UTC-07:00. Daylight saving time applies here, so the offset moves forward one hour from March to November.
Cities and Communities Served by 303
The following places fall inside the 303 calling area:
Other Area Codes in Colorado
These codes also serve Colorado. Area codes are assigned by the North American Numbering Plan Administration (NANPA).
| Area Code | Cities / Coverage |
|---|---|
| 719 | Colorado Springs, Pueblo |
| 720 | Denver (overlay) |
| 970 | Fort Collins, Grand Junction |
| 983 | Denver (overlay) |
See all 5 area codes in Colorado →
Frequently Asked Questions
Where is area code 303?
Area code 303 is in Colorado, United States. It covers Denver.
What time zone is area code 303 in?
Area code 303 rings in the America/Denver time zone (UTC-07:00 standard).
Do I need to dial 1 before area code 303?
Yes, for a long-distance call inside the US and Canada you dial 1 first, then 303, then the seven-digit number. The 1 is the North American long-distance trunk prefix — it is not the country code. From outside North America you dial your exit code then 1 then 303.
Is area code 303 toll-free?
No. 303 is a standard geographic area code, so normal long-distance rates apply unless your plan includes them. Toll-free NANP codes are 800, 833, 844, 855, 866, 877 and 888.