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Single Family ResidenceResidential
$1,323,569$632 / ft²
TopHap EstimateOur estimate of what this home would sell for today, based on nearby sales, the home's size and features, and local price trends. It is a starting point, not an appraisal.· confidence 94How well the pricing models agreed with each other on this home. Higher means the estimate rests on stronger, more consistent data.· as of Sep 24, 2026
Last sold for $1,166,400 on Dec 7, 2018

340 21ST ST

BOULDER, CO 80302
3
Beds
1.8
Baths
2,095 ft²
Living AreaTotal finished area of the structures, from county records. Some counties include shared space like hallways or a building gym, so it may not match a listing.
0.2 ac
Lot SizeThe size of the land the home sits on, from county records.
1955
Year BuiltThe year the home was originally built, according to county records.
1
StoriesHow many floors the home has above ground.
7
RoomsThe total room count in county records. Counties differ on which rooms they count, so compare it loosely.
1
ParkingThe number of parking spaces on the property, including the garage.

Valuation

$1.3M
$1.3M low$1.4M high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$1,166,400 · Dec 7, 2018

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$8,952 (2025)
Assessed ValueThe value the county assigns to this home to calculate property tax. It is often lower than what the home would sell for.$101,225 (2026)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$67,755
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$33,470
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$96,082
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$1,488,600

Climate Risk

Projected Flood DepthHow deep a serious flood is expected to get here at some point in the next 30 years. Shown in inches.26 in
30-Year Flood ChanceThe chance of at least one serious flood here in the next 30 years, not in any single year.6%
FEMA Flood ZoneFEMA's flood zone for this address. Zones starting with A or V are high risk, and lenders usually require flood insurance there.0.2 percent flood zone

Scores 0–100; higher = greater projected risk.

Property Facts

Property TypeThe broad category the county puts this property in, such as residential or commercial.Single Family Residence
StyleThe architectural style of the home, such as ranch or colonial.Ranch
CountyBOULDER
Effective Year BuiltAn adjusted build year that accounts for condition and major remodels. A big renovation can make a home count as newer than it is.1980
Lot (acres)The size of the land the home sits on, from county records.0.20
ConstructionThe main material the home's frame and walls are built from.Masonry/Concrete Masonry Units (Cmus)
RoofThe main material covering the roof, such as asphalt shingle or tile.Asphalt
HeatingThe type of heating system in the home.Forced Air With Air Conditioning
GarageWhether the property has a garage, and details like whether it is attached to the home.Garage, Attached
PoolWhether the property has a pool, and what kind, such as in-ground.No
FeaturesExtra features found in county records. Records are not complete everywhere, so a missing feature does not always mean the home lacks it.Patio · 250 ft²Porch · 244 ft²

Transaction History(8)

Sales and refinances filed with the county for this home. Not every transfer is a normal sale, so check the type before comparing prices.

Assigned SchoolsThe public schools this address is zoned for. Boundaries change, so confirm with the district before you count on it.

E
Creekside Elementary SchoolA+
Elementary · Grades KG–5 · 1.0 mi
H
Boulder High SchoolC
High · Grades 9–12 · 1.2 mi
M
Manhattan School of Arts and AcademicsA-
Middle · Grades 6–8 · 2.0 mi

District: Boulder Valley School District Re-2

Neighborhood · ZIP 80302These are comparison scores, not percentages. 100 equals the national average, so 150 means about 50% above average.

CrimeLocal crime compared with the rest of the country, where 100 is average. It reflects things like population density, income, and how crime gets reported.134
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.92
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.46

Index scale: 100 = US average (tick). Lower is better.

Homes occupiedThe share of homes here that someone lives in. The rest sit empty, including vacation and for-sale homes.91%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.37%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.27%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.1.1%
PopulationHow many people live in this area.31,245
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.324 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$82,366
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$127,191
Average tempThe average temperature here across a full year.45°F
Annual precipHow much rain and melted snow falls here in a typical year.22 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.69%

Owner Tools

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Data by ATTOM. Valuations are automated estimates, not appraisals. Photos from Google Street View and may not depict the current property state.

How this home compares

340 21st St measured against every home in its neighborhood, its ZIP code and its county, using county assessor records refreshed nightly. A home can stand out in one of those areas and look ordinary in another, because each one holds a different mix of homes.

  • Worth more than 84% of homes in Boulder County
  • Costs more per square foot than 88% of homes in Boulder County
  • Older than 90% of homes in Boulder County

What homes are worth in Boulder 80302

Each bar is how many homes fall in that price range. The marker is this home.

This home
$291K$4.4M

This home is worth more than 60% of homes in Boulder 80302.

How it measures up in Boulder 80302

The dot is this home. The mark in the middle is the typical home in Boulder 80302.

Estimated value$1,323,569
CheaperTypical $1,125,749Pricier

Pricier than 60% of homes nearby

Price per ft²$632
CheaperTypical $635Pricier

Pricier than 49% of homes nearby

Living area2,095 ft²
SmallerTypical 2,010 ft²Bigger

Bigger than 53% of homes nearby

Lot size0.2 ac
SmallerTypical 0.24 acBigger

Bigger than 45% of homes nearby

Year built1955
OlderTypical 1970Newer

Newer than 35% of homes nearby

How 340 21st St ranks against every home in each area.
MeasureThis homeBoulder 80302Boulder County
Estimated valuepricier than$1,323,56960% of homes84% of homes
Price per ft²pricier than$63249% of homes88% of homes
Living areabigger than2,095 ft²53% of homes56% of homes
Lot sizebigger than0.2 ac45% of homes58% of homes
Year builtnewer than195535% of homes10% of homes

About 340 21st St

How much is 340 21st St, Boulder, CO worth?

The TopHap Estimate for 340 21st St, Boulder, CO is $1,323,569 as of Sep 24, 2026. The likely range is $1,250,607 to $1,396,531. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 340 21st St, Boulder, CO last sell?

340 21st St, Boulder, CO last sold on Dec 7, 2018 for $1,166,400, according to the county's recorded deed. TopHap holds 2 recorded sales for this parcel.

How big is 340 21st St, Boulder, CO?

340 21st St, Boulder, CO has 3 bedrooms, 1.8 bathrooms, 2,095 square feet of living space and a 0.20-acre lot.

When was 340 21st St, Boulder, CO built?

340 21st St, Boulder, CO was built in 1955, making it 71 years old. It is a ranch home. The building has 1 story.

What schools serve 340 21st St, Boulder, CO?

340 21st St, Boulder, CO is assigned to Creekside Elementary School (elementary), rated A+; Boulder High School (high), rated C; Manhattan School of Arts and Academics (middle), rated A-. All sit in Boulder Valley School District Re-2. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 340 21st St, Boulder, CO compare to other homes in Boulder 80302?

Among the 7,990 homes in Boulder 80302, it is worth more than 60% of them ($1,323,569 against a typical $1,125,749), its price per square foot is higher than 49% of them ($632 against a typical $635), it is bigger than 53% of them (2,095 ft² against a typical 2,010 ft²), its lot is bigger than 45% of them (0.2 ac against a typical 0.24 ac) and it is newer than 35% of them (1955 against a typical 1970). Measured against all of Boulder County, it is worth more than 84% of homes there. These shares are recounted nightly from the full county assessor record for each area, not from active listings.

What are the property taxes on 340 21st St, Boulder, CO?

The 2025 property tax bill for 340 21st St, Boulder, CO was $8,952. The county assessed it at $101,225.

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