Area Code
Colorado, United States
Local Time
4:36 AM
Mountain Time
Area Code
303
State / Province
Colorado
Country
United States
Time Zone
Mountain Time
Area code 303 covers 13 rate centers across Colorado. Rate centers are geographic areas used by telephone companies to determine local calling boundaries.
Use the E.164 format for clickable phone links (RFC 3966):
<a href="tel:+13035550100">+13035550100</a><a href="tel:+13035550199">+13035550199</a>Area code 303 is a North American Numbering Plan (NANP) telephone area code assigned to Colorado, United States. It is one of 4 area codes serving Colorado. As population and demand for phone numbers grew, the region was divided into multiple numbering plan areas to avoid exhausting the available 7-digit number pool.
Yes. 303 is an active North American Numbering Plan (NANP) area code, currently assigned to Colorado, United States. It is safe to answer or dial calls using this area code.
Area code 303 covers 13 rate centers across Colorado. Communities served include Allens Park-lyons, Bennett, Byers, Deckers, Deer Trail, and 8 more localities. Rate centers are the geographic building blocks telephone carriers use to determine local calling boundaries and to assign numbers when a business or individual requests a phone number in a specific city.
All numbers in the 303 area code observe Mountain Time (IANA timezone: America/Denver). Mountain Time is UTC−7 in winter (MST) and UTC−6 in summer (MDT). When placing a call to a 303 number from a different time zone, check the current local time above to avoid calling outside of business hours.
From within Colorado, dial the 7-digit local number directly if calling within the same rate center, or dial 1 + 303 + 7-digit number for long-distance calls within North America. From outside the US or Canada, dial your country's international exit code followed by 1 303 XXX XXXX. The country code for both the United States and Canada in NANP is +1.
Format 303 numbers using E.164 notation as required by RFC 3966: prefix with +1 and omit dashes and parentheses (e.g., +13035550100). This format ensures tel: links work correctly on all mobile browsers and VoIP apps. See the tel: URI formatting guide for complete examples.