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303 Area Code

Area code 303 serves Denver, Aurora, Lakewood, Thornton, Arvada and nearby communities in Colorado. It has been in service since January 1, 1947.

StateColorado
Time zoneMountain
Local time now…
Prefixes in use785
Overlay with720, 983
Projected to run out2069
DenverAuroraLakewoodThorntonArvadaWestminsterCentennialBoulderLongmontBroomfieldCommerce CityLittletonBrightonErieNorthglennEnglewoodWheat RidgeLafayetteFour Square MileLouisvilleSherrelwoodFrederickWelbyGreenwood VillageFederal HeightsCherry CreekBerkleyGunbarrelLochbuieDerbyTwin LakesDaconoCherry Hills VillageSheridanDove ValleyShaw HeightsTodd CreekMeridianDenverThorntonCentennialBoulderLongmont
Cities and towns served by area code 303

Who issues 303 numbers

Mobile 17%VoIP and cable 18%Landline 65%

Share of the 785 prefixes (the three digits after 303) assigned to each type of carrier. Classification by carrier name, approximate.

CarrierPrefixes
Lumen (Qwest)449
Verizon Wireless60
Lumen (Level 3)60
T-Mobile39
AT&T Mobility35
Spok31
Verizon Business (MCImetro)31
AT&T (Teleport)28

Cities and towns in area code 303

CityPopulationOther area codes
Denver740,613720, 983
Aurora410,053720, 983
Lakewood156,927720, 983
Thornton147,766720, 983
Arvada122,901720, 983
Westminster116,182720, 983
Centennial108,658720, 983
Boulder105,689720, 983
Longmont100,109720, 983
Broomfield79,174720, 983
Commerce City72,345720, 983
Littleton46,246720, 983
Brighton45,395720
Erie40,904720, 983
Northglenn38,893720, 983
Englewood35,305720, 983
Wheat Ridge32,081720, 983
Lafayette30,116720, 983
Four Square Mile21,788720, 983
Louisville20,581720, 983
Sherrelwood19,368720, 983
Frederick18,241720, 983
Welby16,232720, 983
Greenwood Village15,323720, 983
Federal Heights14,075720, 983
Cherry Creek11,011720, 983
Berkley10,838720, 983
Gunbarrel10,424720, 983
Lochbuie8,776720
Derby8,692720, 983
Twin Lakes8,279720, 983
Dacono6,844720, 983
Cherry Hills Village6,389720, 983
Sheridan5,972720, 983
Dove Valley5,313720, 983
Shaw Heights5,309720, 983
Todd Creek5,069720, 983
Meridian5,058720, 983

Got a call from 303?

A 303 number was originally issued in Colorado, but that does not prove the caller is there. 18% of 303 prefixes belong to VoIP and cable providers, whose numbers can be bought online and used from anywhere. Caller ID can also be spoofed, so treat urgent requests for money, codes or passwords from any area code with suspicion, and call back on a number you already know.

All 785 prefixes in area code 303

Format: (303) XXX-YYYY. Carrier is the company the block was originally assigned to; numbers may since have been ported to another carrier.

Questions about area code 303

Where is area code 303?
Area code 303 is in Colorado. It covers Denver, Aurora, Lakewood, Thornton, Arvada, Westminster and 32 more cities and towns.
What time zone is area code 303?
Area code 303 is in the Mountain time zone.
Is 303 a toll-free number?
No. 303 is a geographic area code in Colorado. Toll-free numbers in the US start with 800, 833, 844, 855, 866, 877 or 888.
Why does 303 share its area with 720 and 983?
303, 720 and 983 form an overlay: they cover the same territory, so new numbers there can get any of these codes, and local calls need all 10 digits.
Will area code 303 run out of numbers?
NANPA's latest forecast projects the 303/720/983 overlay to exhaust in the second quarter of 2069. Before that happens, a new area code is usually added as an overlay; existing numbers keep their code.

Other area codes in Colorado