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CondominiumResidential
$893,209$602 / 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 92How 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 $173,000 on Oct 20, 1997

21 BELKNAP ST

ARLINGTON, MA 02474
Building report
3
Beds
2
Baths
1,484 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.
0.11 ac
Lot SizeThe size of the land the home sits on, from county records.
1910
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.

Valuation

$893K
$824K low$962K high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$173,000 · Oct 20, 1997

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$6,750 (2026)
Assessed ValueThe value the county assigns to this home to calculate property tax. It is often lower than what the home would sell for.$632,600 (2026)
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$632,600
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$608,600
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$762,083

Property Facts

Property TypeThe broad category the county puts this property in, such as residential or commercial.Condominium
StyleThe architectural style of the home, such as ranch or colonial.Condo/Apartment
CountyMIDDLESEX
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.1975
ConstructionThe main material the home's frame and walls are built from.Frame (Unspecified)
RoofThe main material covering the roof, such as asphalt shingle or tile.Asphalt
HeatingThe type of heating system in the home.Hot Water
CoolingThe type of cooling or air conditioning in the home.Yes
PoolWhether the property has a pool, and what kind, such as in-ground.No

Transaction History(4)

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
R.J. Hardy Elementary SchoolA
Elementary · Grades KG–5 · 0.3 mi
H
Arlington High SchoolA+
High · Grades 9–12 · 0.9 mi
M
Ottoson Middle SchoolA+
Middle · Grades 7–8 · 1.6 mi

District: Arlington School District

Neighborhood · ZIP 02474These 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.93
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.106
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.79

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.96%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.33%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.5.0%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.1.2%
PopulationHow many people live in this area.28,960
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.8,757 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$135,066
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$157,393
Average tempThe average temperature here across a full year.49°F
Annual precipHow much rain and melted snow falls here in a typical year.47 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.58%

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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

21 Belknap 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 less than 67% of homes in Arlington 02474
  • Costs more per square foot than 77% of homes in Middlesex County
  • Smaller than 71% of homes in Arlington 02474
  • Has a smaller lot than 86% of homes in Middlesex County
  • Older than 90% of homes in Arlington 02474

What homes are worth in Arlington 02474

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

This home
$335K$2.1M

This home is worth more than 33% of homes in Arlington 02474.

How it measures up in Arlington 02474

The dot is this home. The mark in the middle is the typical home in Arlington 02474.

Estimated value$893,209
CheaperTypical $1,028,125Pricier

Pricier than 33% of homes nearby

Price per ft²$602
CheaperTypical $590Pricier

Pricier than 54% of homes nearby

Living area1,484 ft²
SmallerTypical 1,980 ft²Bigger

Bigger than 29% of homes nearby

Lot size0.11 ac
SmallerTypical 0.14 acBigger

Bigger than 20% of homes nearby

Year built1910
OlderTypical 1933Newer

Newer than 10% of homes nearby

How 21 Belknap St ranks against every home in each area.
MeasureThis homeArlington 02474Middlesex County
Estimated valuepricier than$893,20933% of homes62% of homes
Price per ft²pricier than$60254% of homes77% of homes
Living areabigger than1,484 ft²29% of homes34% of homes
Lot sizebigger than0.11 ac20% of homes14% of homes
Year builtnewer than191010% of homes19% of homes

About 21 Belknap St

How much is 21 Belknap St, Arlington, MA worth?

The TopHap Estimate for 21 Belknap St, Arlington, MA is $893,209 as of Sep 24, 2026. The likely range is $824,442 to $961,976. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 21 Belknap St, Arlington, MA last sell?

21 Belknap St, Arlington, MA last sold on Oct 20, 1997 for $173,000, according to the county's recorded deed. TopHap holds 2 recorded sales for this parcel.

How big is 21 Belknap St, Arlington, MA?

21 Belknap St, Arlington, MA has 3 bedrooms, 2 bathrooms and 1,484 square feet of living space.

When was 21 Belknap St, Arlington, MA built?

21 Belknap St, Arlington, MA was built in 1910, making it 116 years old. It is a condo/apartment home. The building has 1 story.

What schools serve 21 Belknap St, Arlington, MA?

21 Belknap St, Arlington, MA is assigned to R.J. Hardy Elementary School (elementary), rated A; Arlington High School (high), rated A+; Ottoson Middle School (middle), rated A+. All sit in Arlington School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 21 Belknap St, Arlington, MA compare to other homes in Arlington 02474?

Among the 8,570 homes in Arlington 02474, it is worth more than 33% of them ($893,209 against a typical $1,028,125), its price per square foot is higher than 54% of them ($602 against a typical $590), it is bigger than 29% of them (1,484 ft² against a typical 1,980 ft²), its lot is bigger than 20% of them (0.11 ac against a typical 0.14 ac) and it is newer than 10% of them (1910 against a typical 1933). Measured against all of Middlesex County, it is worth more than 62% 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 21 Belknap St, Arlington, MA?

The 2026 property tax bill for 21 Belknap St, Arlington, MA was $6,750. The county assessed it at $632,600.

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