ZIP codes
153
Area Code 303
Explore ZIP codes in area code 303 — covering CO — 153 ZIP codes — 3,399,753 residents. Population, income, and housing at a glance.
Population
3,399,753
States
CO
Median household income (avg.)
$106,547
Average home value
$595,771
Where is area code 303?
Area code 303 maps to 153 indexable ZIP codes on US5 across CO, with a combined ZIP-area population of about 3,399,753.
Among places with the most population in this NPA on US5 are Denver, CO, Aurora, CO, Thornton, CO, Lakewood, CO, and Centennial, CO. Open any ZIP below for full demographics, housing, and nearby services.
The most populous ZIP currently listed for 303 is 80134 (about 77,814 residents).
Income and housing in 303
Across ZIPs with income data in area code 303, the average median household income is about $106,547 — about 42% above the U.S. median ($75,149).
Average median home value across those ZIPs is about $595,771.
On this page’s income ranking, ZIP 80108 is near the top at about $178,670.
How area code 303 numbering works
In the North American Numbering Plan, the first three digits of a 10-digit phone number are the Numbering Plan Area (NPA), commonly called the area code. Digits 4–6 are the central office code (NXX / “exchange”), and the last four digits identify the individual line.
US5’s 303 page groups ZIP codes that are associated with this NPA in published geography data. That is a place-based view — it is not a live directory of every phone number assigned to 303, and overlays or split NPAs can mean multiple area codes serve the same metro.
Scams and caller ID spoofing
Seeing area code 303 on caller ID does not prove the caller is physically in CO. Spoofing tools can display almost any NPA, including local-looking numbers used in IRS, bank, warranty, and “grandparent” scams.
If you receive an unexpected call about taxes, arrests, or locked accounts: hang up, do not share codes or remote-access software, and contact the organization using a number from its official website or your statement — not a number the caller provides. US5 publishes geography for research; it does not verify live callers.
ZIP codes in area code 303
Frequently asked questions
Where is area code 303?
Area code 303 is associated with ZIP codes in CO on US5, covering about 3,399,753 combined ZIP-area residents across 153 codes. Browse the ZIP table on this page for cities and counties.
How many ZIP codes are in area code 303?
US5 currently lists 153 indexable ZIP codes for area code 303. Counts can change as geography publishes update.
What is the average income in area code 303?
The average of ZIP median household incomes in area code 303 is about $106,547 (about 42% above the U.S. median ($75,149)). Individual neighborhoods vary — sort the ZIP table by income to compare.
What is an NXX or “number block” in area code 303?
After the area code, the next three digits (NXX) identify a central office / exchange “block” of up to 10,000 numbers. US5 focuses on ZIP geography for 303; for live number assignment details, use official NANPA / carrier resources.
Does a 303 caller ID mean the person is local?
No. Caller ID can be spoofed to show area code 303 even when the caller is elsewhere. Treat unexpected calls about money, arrests, or account lockouts as suspicious and verify through official channels.
How can I avoid phone scams that use area code 303?
Do not trust caller ID alone. Never send gift cards, wire money, or install remote-access apps because a caller claims to be from the IRS, a bank, or tech support. Hang up and call back using a published number from a statement or official website.
What cities use area code 303?
Larger population clusters on US5 for 303 include Denver, CO, Aurora, CO, Thornton, CO, Lakewood, CO, and Centennial, CO. Open linked ZIP pages for neighborhood-level demographics.