Area code 303
Colorado · Denver, Boulder
- Area code
- 303
- Country
- United States
- Region
- Colorado
- Major cities
- Denver, Boulder
- Time zone
- America/Denver
- Note
- Denver metro area code.
This is a domestic area code inside United States. It is not the international calling code.
Frequently asked questions
Which cities use area code 303?
Area code 303 serves Colorado in United States, including Denver, Boulder.
What region does area code 303 cover?
Area code 303 covers Colorado. Area codes route calls to a specific city or region within a country's national telephone network.
What is the difference between an area code and a calling code?
A calling code routes a call across borders to a national network, while an area code routes it to a city or region inside that network. For a United States number, the country calling code is the international prefix and 303 is the domestic area code.
What time zone is area code 303 in?
Area code 303 is in the IANA time zone America/Denver.
Is area code 303 the international calling code?
No. 303 is a domestic area code inside United States, not the international calling code. To call this region from abroad, you dial the country's calling code first, then 303 and the local number.