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Single Family ResidenceResidential
$715,476$352 / 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 Jul 14, 2026

21 MARTIN ST

ACTON, MA 01720
3
Beds
1.5
Baths
2,033 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.
4.02 ac
Lot SizeThe size of the land the home sits on, from county records.
1855
Year BuiltThe year the home was originally built, according to county records.
2
StoriesHow many floors the home has above ground.

Valuation

$715K
$673K low$758K high

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$11,504 (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.$670,800 (2025)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$297,600
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$373,200
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$870,485

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.79 in
30-Year Flood ChanceThe chance of at least one serious flood here in the next 30 years, not in any single year.51%
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.1 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.Historical
CountyMIDDLESEX
Lot (acres)The size of the land the home sits on, from county records.4.02
RoofThe main material covering the roof, such as asphalt shingle or tile.Metal
HeatingThe type of heating system in the home.Forced Air With Air Conditioning
PoolWhether the property has a pool, and what kind, such as in-ground.No

Transaction History(2)

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.

M
R. J. Grey Junior High SchoolA
Middle · Grades 7–8 · 1.1 mi
E
Merriam Elementary SchoolB
Elementary · Grades KG–6 · 1.2 mi
H
Acton - Boxborough Regional High SchoolA
High · Grades 9–12 · 1.3 mi

District: Acton-Boxborough School District

Neighborhood · ZIP 01720These 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.71
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.104
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.72

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.97%
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.2.6%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.1.3%
PopulationHow many people live in this area.24,473
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.1,210 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$148,952
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$187,397
Average tempThe average temperature here across a full year.48°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 Martin 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 71% of homes in Acton 01720
  • Costs less per square foot than 87% of homes in Acton 01720
  • Has a bigger lot than 93% of homes in Middlesex County
  • Among the oldest homes in Middlesex County

What homes are worth in Acton 01720

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

This home
$236K$1.7M

This home is worth more than 29% of homes in Acton 01720.

How it measures up in Acton 01720

The dot is this home. The mark in the middle is the typical home in Acton 01720.

Estimated value$715,476
CheaperTypical $875,331Pricier

Pricier than 29% of homes nearby

Price per ft²$352
CheaperTypical $416Pricier

Pricier than 13% of homes nearby

Living area2,033 ft²
SmallerTypical 2,079 ft²Bigger

Bigger than 48% of homes nearby

Lot size4.02 ac
SmallerTypical 0.7 acBigger

Bigger than 82% of homes nearby

Year built1855
OlderTypical 1971Newer

Newer than 2% of homes nearby

How 21 Martin St ranks against every home in each area.
MeasureThis homeActon 01720Middlesex County
Estimated valuepricier than$715,47629% of homes40% of homes
Price per ft²pricier than$35213% of homes19% of homes
Living areabigger than2,033 ft²48% of homes58% of homes
Lot sizebigger than4.02 ac82% of homes93% of homes
Year builtnewer than18552% of homesalmost no homes

About 21 Martin St

How much is 21 Martin St, Acton, MA worth?

The TopHap Estimate for 21 Martin St, Acton, MA is $715,476 as of Jul 14, 2026. The likely range is $673,270 to $757,682. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 21 Martin St, Acton, MA last sell?

21 Martin St, Acton, MA last sold on Jan 1, 1900, according to the county's recorded deed.

How big is 21 Martin St, Acton, MA?

21 Martin St, Acton, MA has 3 bedrooms, 1.5 bathrooms, 2,033 square feet of living space and a 4.02-acre lot.

When was 21 Martin St, Acton, MA built?

21 Martin St, Acton, MA was built in 1855, making it 171 years old. It is a historical home. The building has 2 stories.

What schools serve 21 Martin St, Acton, MA?

21 Martin St, Acton, MA is assigned to R. J. Grey Junior High School (middle), rated A; Merriam Elementary School (elementary), rated B; Acton - Boxborough Regional High School (high), rated A. All sit in Acton-Boxborough School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 21 Martin St, Acton, MA compare to other homes in Acton 01720?

Among the 7,508 homes in Acton 01720, it is worth more than 29% of them ($715,476 against a typical $875,331), its price per square foot is higher than 13% of them ($352 against a typical $416), it is bigger than 48% of them (2,033 ft² against a typical 2,079 ft²), its lot is bigger than 82% of them (4.02 ac against a typical 0.7 ac) and it is newer than 2% of them (1855 against a typical 1971). Measured against all of Middlesex County, it is worth more than 40% 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 Martin St, Acton, MA?

The 2025 property tax bill for 21 Martin St, Acton, MA was $11,504. The county assessed it at $670,800.

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