Area Code 303 – (Location, Timezone) Read All Details Here!

Area Code 303

Area code 303 is telephonic in the North American Numbering Plan and serves the north-central portion of the state of Colorado.


Area code 303 is in Colorado State serves the counties such as Denver, Adams, Jefferson, Boulder, Broomfield, Douglas, Arapahoe, Weld, Clear Creek, and lake county. It also includes Denver, Aurora, Thornton, Westminster, Commerce City, Northglenn, Brighton, Federal Heights, Bennett, Strasburg, Lakewood, Arvada, Wheat Ridge, Golden, Evergreen, Boulder, Longmont, Lafayette, Erie, Louisville, Superior, Broomfield, Castle Rock, Parker, Littleton, Englewood, Greenwood Village, Cherry Hills Village, Sheridan, Byers, Deer Trail, Frederick, Fort Lupton, Hudson, Keenesburg, Roggen, Georgetown, and Twin Lakes cities.

Time zone

The area code 303 lies in the Mountain time zone.


  • It was one of the original 86 NANP area codes originated in 1947.
  • It served the entire state of Colorado for forty years. Although the population increased in second half of the 20th century, especially in the Denver area.
  • At the end of 1980s, because of rapid increase in population and use of other communication devices, there was a need for a new area code. As area’s need for more phone numbers rises.
  • So, on March 5, 1988, a new area code 719 formed and covered southeastern Colorado.
  • Another area code 970 came to cover the northeastern and western portions of area code 303, on April 2, 1995. Resulted in reducing 303 to the Denver-Boulder area.
  • Therefore, it was the only Colorado area code in 1995 split that did not border another state.
  • The 1995 split was a long-term solution but within two years the area’s population was growing fast so that area code 720 fromed in the 303 service area to create an overlay, on September 1, 1998.

More Info about Area code 303

The Denver metropolitan area is under the service area of area code 303. According to official predictions in 2020, this area code may exhaust again by 2023. To fulfill the requirements of telecommunication needs of that area, a new 983 area code will come into service in this area on April 12, 2022.

How to make a call in an area code overlay?

  • In an overlay, the new area code serves the same area as the existing area code. It serves the same geographic area. In this overlay area code
  • Existing phone numbers and local calling procedures remain same.
  • Ten-digit dialing (area code + seven-digit number) is necessary.
  • In an overlay situation, you can call to seven-digit phone number of same area but with different area code by following 10-digit dialing.
  • With seven-digit dialing a caller can dial only the local seven-digit number, without the area code.
  • The 303/720 area is one of the largest toll-free calling zones in the western United States except Roggen, Brighton, and Wiggins.
  • In this area long-distance charges are not applied to any calls made from one phone to another in the area.
  • All users must dial ten- digits in the 303/720 area except for Roggen.

For More You May Also Read: Area Code 208

Leave a Comment