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CondominiumResidential
$679,418$548 / 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 98How well the pricing models agreed with each other on this home. Higher means the estimate rests on stronger, more consistent data.· as of Aug 30, 2026
Last sold for $626,389 on Jan 11, 2021

21 KING ST

BELMONT, MA 02478
2
Beds
1
Baths
1,240 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.
4,271 ft²
Lot SizeThe size of the land the home sits on, from county records.
1926
Year BuiltThe year the home was originally built, according to county records.
1
StoriesHow many floors the home has above ground.
6
RoomsThe total room count in county records. Counties differ on which rooms they count, so compare it loosely.

Valuation

$679K
$663K low$696K high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$626,389 · Jan 11, 2021

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$7,358 (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.$646,000 (2025)
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$646,000
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$778,905

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.2008
ConstructionThe main material the home's frame and walls are built from.Frame (Unspecified)
HeatingThe type of heating system in the home.Steam
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
Daniel ButlerA+
Elementary · Grades KG–3 · 0.3 mi
M
Winthrop L Chenery Upper Elementary SchoolA-
Middle · Grades 4–6 · 0.8 mi
H
Belmont High SchoolA+
High · Grades 9–12 · 1.4 mi

District: Belmont School District

Neighborhood · ZIP 02478These 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.55
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.103
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.74

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.95%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.28%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.3.8%
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.27,636
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.5,959 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$162,650
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$213,185
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 King 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 96% of homes in Belmont 02478
  • Costs less per square foot than 91% of homes in Belmont 02478
  • Smaller than 89% of homes in Belmont 02478
  • Has a smaller lot than 93% of homes in Belmont 02478
  • Older than 71% of homes in Middlesex County

What homes are worth in Belmont 02478

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

This home
$580K$3.5M

This home is worth more than 4% of homes in Belmont 02478.

How it measures up in Belmont 02478

The dot is this home. The mark in the middle is the typical home in Belmont 02478.

Estimated value$679,418
CheaperTypical $1,473,338Pricier

Pricier than 4% of homes nearby

Price per ft²$548
CheaperTypical $725Pricier

Pricier than 9% of homes nearby

Living area1,240 ft²
SmallerTypical 2,112 ft²Bigger

Bigger than 11% of homes nearby

Lot size4,271 ft²
SmallerTypical 0.16 acBigger

Bigger than 7% of homes nearby

Year built1926
OlderTypical 1930Newer

Newer than 40% of homes nearby

How 21 King St ranks against every home in each area.
MeasureThis homeBelmont 02478Middlesex County
Estimated valuepricier than$679,4184% of homes37% of homes
Price per ft²pricier than$5489% of homes68% of homes
Living areabigger than1,240 ft²11% of homes22% of homes
Lot sizebigger than4,271 ft²7% of homes11% of homes
Year builtnewer than192640% of homes29% of homes

About 21 King St

How much is 21 King St, Belmont, MA worth?

The TopHap Estimate for 21 King St, Belmont, MA is $679,418 as of Aug 30, 2026. The likely range is $662,795 to $696,041. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 21 King St, Belmont, MA last sell?

21 King St, Belmont, MA last sold on Jan 11, 2021 for $626,389, according to the county's recorded deed. TopHap holds 3 recorded sales for this parcel.

How big is 21 King St, Belmont, MA?

21 King St, Belmont, MA has 2 bedrooms, 1 bathrooms and 1,240 square feet of living space.

When was 21 King St, Belmont, MA built?

21 King St, Belmont, MA was built in 1926, making it 100 years old. It is a condo/apartment home. The building has 1 story.

What schools serve 21 King St, Belmont, MA?

21 King St, Belmont, MA is assigned to Daniel Butler (elementary), rated A+; Winthrop L Chenery Upper Elementary School (middle), rated A-; Belmont High School (high), rated A+. All sit in Belmont School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 21 King St, Belmont, MA compare to other homes in Belmont 02478?

Among the 7,995 homes in Belmont 02478, it is worth more than 4% of them ($679,418 against a typical $1,473,338), its price per square foot is higher than 9% of them ($548 against a typical $725), it is bigger than 11% of them (1,240 ft² against a typical 2,112 ft²), its lot is bigger than 7% of them (4,271 ft² against a typical 0.16 ac) and it is newer than 40% of them (1926 against a typical 1930). Measured against all of Middlesex County, it is worth more than 37% 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 King St, Belmont, MA?

The 2025 property tax bill for 21 King St, Belmont, MA was $7,358. The county assessed it at $646,000.

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