720 Area Code: Denver Location, Time Zone & Scam Check (2026)
The 720 area code covers Denver-Boulder, Colorado — the Mile High City. Learn its history, Mountain time zone, scam risk, 300+ days of sunshine, and how to call Denver internationally.
Quick Answer
The 720 area code covers the Denver-Boulder metropolitan area in north-central Colorado. It's in the Mountain time zone (UTC-7 / UTC-6 during DST). 720 is an overlay of the original 303, serving approximately 3.9 million people along Colorado's Front Range — the Mile High City and beyond.
Where Is the 720 Area Code?
The 720 area code serves the Denver-Boulder metropolitan corridor — Colorado's economic and cultural heartbeat. The coverage area stretches from Boulder and Longmont in the north, west to the Rocky Mountain foothills near Golden, south through suburbs like Castle Rock and Parker, and east across the plains through Aurora (the state's third-largest city).
As an overlay, 720 covers the exact same 10 counties as the original 303: Denver, Jefferson, Arapahoe, Adams, Boulder, Douglas, Broomfield, Clear Creek, Gilpin, and part of Weld County. A third overlay, 983, was added in 2022. Together, the region is home to roughly 3.9 million people.
Neighboring Area Codes
Colorado Springs
Pueblo (south)
Fort Collins, Vail
Grand Junction (north/west)
Denver-Boulder
(newest overlay, 2022)
History of the 720 Area Code
Colorado's area code story begins with 303 in 1947 — one of the original 86 codes in the North American Numbering Plan. For 40 years, 303 was the only area code in the entire state of Colorado. That changed in the late 1980s when population growth along the Front Range began exhausting available numbers.
After splitting off Colorado Springs (719 in 1988) and the northern/western regions (970 in 1995), Denver-Boulder still couldn't keep up with demand. The explosion of cell phones, pagers, and fax machines in the 1990s burned through 303 numbers fast. On June 1, 1998, area code 720 went live as the first overlay for the Denver metro.
| Code | Year | Type | What Happened |
|---|---|---|---|
| 303 | 1947 | Original | One of the original 86 area codes. Covered the entire state of Colorado for 40 years. |
| 719 | 1988 | Split | March 5 — southeastern Colorado (Colorado Springs, Pueblo) split from 303. |
| 970 | 1995 | Split | April 2 — northeastern and western Colorado (Fort Collins, Grand Junction, Vail) split from 303. |
| 720 | 1998 | 1st Overlay | June 1 — overlaid on the Denver-Boulder metro. 10-digit dialing became mandatory. Driven by cell phone and pager boom. |
| 983 | 2022 | 2nd Overlay | June 17 — newest overlay for Denver-Boulder, added due to continued number exhaustion in 303/720. |
Cultural note: In Denver, 303 carries the same kind of local cachet that 212 does in New York or 214 in Dallas. It's become a cultural symbol — you'll see "303" on T-shirts, tattoos, and local business branding throughout the city. The "303 Day" (March 3rd) is an unofficial holiday celebrating Denver identity.
720 Area Code Time Zone & Best Time to Call
The entire 720 coverage area is in the Mountain Time Zone (MT) — UTC-7 during standard time and UTC-6 during daylight saving time.
Best Time to Call Denver
- Business calls: 9:00 AM – 5:00 PM MT
- Personal calls: 10:00 AM – 8:00 PM MT
- Avoid: Before 8:00 AM and after 9:00 PM
- From East Coast (ET): Subtract 2 hours (12 PM ET = 10 AM MT)
- From West Coast (PT): Add 1 hour (9 AM PT = 10 AM MT)
International Time Differences
- London (GMT/BST): Denver is 7 hours behind
- Mumbai (IST): Denver is 12.5 hours behind
- Tokyo (JST): Denver is 16 hours behind
- Sydney (AEST): Denver is 17 hours behind
- Mexico City (CST): Denver is 1 hour behind
Use our Best Time to Call tool to convert between Denver and any time zone instantly.
Is 720 a Spam Area Code?
The 720 area code is completely legitimate — it serves nearly 4 million people in metro Denver. But Colorado has a growing robocall problem: in the first nine months of 2025, Coloradans received over 290 million scam or unwanted calls — a six-year high. In September 2025 alone, Colorado phones got an estimated 51.6 million robocalls.
Colorado ranks #4 in the nation for imposter scam reports (per FTC data, first half of 2025). The state attorney general has issued formal warnings to 9 phone companies for allowing illegal robocall traffic. Only 44% of phone providers have fully implemented required robocall-fighting technology (STIR/SHAKEN).
| Scam Type | Prevalence | How It Works |
|---|---|---|
| Imposter scams | #1 type | Callers pretending to be from the IRS, Social Security, or a utility company — Colorado ranks #4 nationally for imposter scam reports |
| Auto warranty expiration | ~10% | Persistent robocalls about vehicle warranty — one of the most common robocall categories in Colorado |
| Tech support fraud | ~8% | Callers claiming your computer is infected, requesting remote access or payment |
| Package delivery scams | Rising | Texts/calls claiming USPS or FedEx packages can't be delivered — link to phishing sites |
| Student loan forgiveness | ~5% | Fake calls about loan forgiveness programs, targeting younger Coloradans |
Got a suspicious call from a 720 number? Use our Spam Number Checker to look up the number. You can also use the Area Code Lookup tool to verify where any US number originates.
How to Call a 720 Number from Outside the US
Dialing Format by Country
+1 720 XXX XXXX00 1 720 XXX XXXX00 1 720 XXX XXXX00 1 720 XXX XXXX0011 1 720 XXX XXXXCall Denver Numbers with BubblyPhone
Need to call someone in the 720 area code? BubblyPhone offers crystal-clear international calls to Denver at rates starting from $0.01/min. No app download needed — call directly from your browser.
View RatesMajor Cities & Communities in the 720 Area Code
| City | Population (2025 est.) | County |
|---|---|---|
| Denver | 731,868 | Denver |
| Aurora | 407,211 | Arapahoe / Adams |
| Lakewood | 157,014 | Jefferson |
| Thornton | 147,813 | Adams |
| Arvada | 121,250 | Jefferson / Adams |
| Westminster | 114,964 | Adams / Jefferson |
| Centennial | 109,015 | Arapahoe |
| Boulder | 106,399 | Boulder |
| Longmont | 99,971 | Boulder / Weld |
| Castle Rock | 85,544 | Douglas |
| Broomfield | 79,280 | Broomfield |
| Commerce City | 72,109 | Adams |
| Parker | 67,128 | Douglas |
| Littleton | 44,699 | Arapahoe / Jefferson |
| Brighton | 44,267 | Adams / Weld |
| Northglenn | 38,348 | Adams |
| Englewood | 35,642 | Arapahoe |
| Golden | 20,089 | Jefferson |
What Makes the 720 Area Code Region Unique
The Mile High City
Denver sits at exactly 5,280 feet (one mile) above sea level. The 13th step on the west side of the Colorado State Capitol is engraved "ONE MILE ABOVE SEA LEVEL." At Coors Field, the seats in the 20th row of the upper deck are painted purple to mark the exact 5,280-foot elevation line.
Red Rocks Amphitheatre
The only naturally formed, acoustically perfect outdoor amphitheater in the world. Flanked by two 400-foot sandstone monoliths in Morrison, CO. Capacity 9,525. Named a National Historic Landmark in 2015 and the #1 top-grossing concert venue of any size in the world (2021).
DIA: Bigger Than Manhattan
Denver International Airport covers 53 square miles — the largest airport by area in North America and twice the size of Manhattan. Its 16,000-foot runway is the longest public-use runway in North America. The iconic tent-like roof mimics the Rocky Mountains. And yes — the "Blucifer" horse statue (32 feet tall, glowing red eyes) killed its creator during construction.
More Sunshine Than San Diego
Denver averages 300+ days of sunshine per year — more annual hours of sunshine than Miami or San Diego. The 69% annual sunshine percentage is counterintuitive for a Mountain West city, but Denver's dry air and high altitude make for remarkably clear skies.
Denver by the Numbers
Notable Landmarks in the 720 Area Code
Coors Field
Home of the Colorado Rockies (MLB). The highest-elevation Major League ballpark at ~5,200 feet — over 4,000 feet higher than the next-highest park. Baseballs fly 9% farther here due to the thinner air.
Molson Coors Brewery (Golden)
The second-largest beer-making facility in the world, employing 2,000 people. Founded in 1873. Free tours available — one of Colorado's most visited attractions.
University of Colorado Boulder
Flagship university with distinctive Tuscan-style architecture. Home to 5 Nobel Prize laureates, the National Center for Atmospheric Research, and one of the top aerospace engineering programs in the country.
Denver Art Museum
Designed by architect Daniel Libeskind (Frederic C. Hamilton Building), the museum houses 70,000+ works and is one of the largest art museums between Chicago and the West Coast.
Craft Beer Capital
Denver has 100+ brewpubs, breweries, and taprooms. Wynkoop Brewing Company (1988) is Colorado's first brewpub. Great Divide Brewing (1994) is one of the most decorated breweries in America.
Major Companies in the 720 Area Code
The Denver metro's Fortune 1000 companies collectively generate approximately $84 billion in annual revenue and employ 176,000 people. The region is particularly strong in aerospace, energy, and technology.
| Company | Rank | Sector | HQ |
|---|---|---|---|
| Arrow Electronics | #102 | Electronics Distribution | Centennial |
| DISH Network | #197 | TV / Streaming | Englewood |
| Ball Corporation | #260 | Aerospace / Packaging | Westminster |
| VF Corporation | #263 | Apparel (The North Face, Vans) | Denver |
| Newmont Corporation | Fortune 500 | Gold Mining (world's largest) | Denver |
| DaVita | Fortune 500 | Healthcare / Kidney Care | Denver |
| Lockheed Martin Space | Division HQ | Aerospace & Defense | Littleton |
| Molson Coors | Fortune 500 | Beverages | Golden |
| Western Union | Fortune 500 | Financial Services | Denver |
| Liberty Media | Fortune 500 | Media / Owns Formula 1 | Englewood |
Related Area Codes
Frequently Asked Questions About the 720 Area Code
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