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Single Family ResidenceResidential
$690,941$320 / 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 $219,000 on Aug 10, 1992

866 DIAMOND DR

GAITHERSBURG, MD 20878
3.5
Baths
2,156 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.
0.21 ac
Lot SizeThe size of the land the home sits on, from county records.
1971
Year BuiltThe year the home was originally built, according to county records.
2
StoriesHow many floors the home has above ground.
1
ParkingThe number of parking spaces on the property, including the garage.

Valuation

$691K
$651K low$731K high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$219,000 · Aug 10, 1992

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$6,377 (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.$550,300 (2026)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$239,800
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$310,500
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$510,800
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$550,300

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.Bi-Level
CountyMONTGOMERY
Lot (acres)The size of the land the home sits on, from county records.0.21
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.Composition Shingle
HeatingThe type of heating system in the home.Yes
CoolingThe type of cooling or air conditioning in the home.Central
FireplaceWhether the home has a fireplace, and what kind.Yes
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

Transaction History(1)

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
Diamond Elementary SchoolA
Elementary · Grades KG–5 · 0.2 mi
M
Lakelands Park Middle SchoolB-
Middle · Grades 6–8 · 1.4 mi
H
Northwest High SchoolB+
High · Grades 9–12 · 2.6 mi

District: Montgomery County Public Schools

Neighborhood · ZIP 20878These 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.62
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.89
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.42

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.35%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.4.9%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.0.9%
PopulationHow many people live in this area.66,167
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.2,976 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$145,457
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$176,656
Average tempThe average temperature here across a full year.54°F
Annual precipHow much rain and melted snow falls here in a typical year.43 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.57%

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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

866 Diamond Dr 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 70% of homes in Gaithersburg
  • Costs more per square foot than 69% of homes in Gaithersburg
  • Bigger than 65% of homes in Gaithersburg
  • Has a bigger lot than 86% of homes in Gaithersburg
  • Older than 90% of homes in Gaithersburg 20878

What homes are worth in Gaithersburg 20878

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

This home
$186K$1.6M

This home is worth more than 43% of homes in Gaithersburg 20878.

How it measures up in Gaithersburg 20878

The dot is this home. The mark in the middle is the typical home in Gaithersburg 20878.

Estimated value$690,941
CheaperTypical $740,407Pricier

Pricier than 43% of homes nearby

Price per ft²$320
CheaperTypical $308Pricier

Pricier than 59% of homes nearby

Living area2,156 ft²
SmallerTypical 2,268 ft²Bigger

Bigger than 47% of homes nearby

Lot size0.21 ac
SmallerTypical 0.11 acBigger

Bigger than 62% of homes nearby

Year built1971
OlderTypical 1988Newer

Newer than 10% of homes nearby

How 866 Diamond Dr ranks against every home in each area.
MeasureThis homeGaithersburgGaithersburg 20878Montgomery County
Estimated valuepricier than$690,94170% of homes43% of homes58% of homes
Price per ft²pricier than$32069% of homes59% of homes57% of homes
Living areabigger than2,156 ft²65% of homes47% of homes56% of homes
Lot sizebigger than0.21 ac86% of homes62% of homes64% of homes
Year builtnewer than197114% of homes10% of homes40% of homes

About 866 Diamond Dr

How much is 866 Diamond Dr, Gaithersburg, MD worth?

The TopHap Estimate for 866 Diamond Dr, Gaithersburg, MD is $690,941 as of Sep 24, 2026. The likely range is $650,722 to $731,160. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 866 Diamond Dr, Gaithersburg, MD last sell?

866 Diamond Dr, Gaithersburg, MD last sold on Aug 10, 1992 for $219,000, according to the county's recorded deed.

How big is 866 Diamond Dr, Gaithersburg, MD?

866 Diamond Dr, Gaithersburg, MD has 3.5 bathrooms, 2,156 square feet of living space and a 0.21-acre lot.

When was 866 Diamond Dr, Gaithersburg, MD built?

866 Diamond Dr, Gaithersburg, MD was built in 1971, making it 55 years old. It is a bi-level home. The building has 2 stories.

What schools serve 866 Diamond Dr, Gaithersburg, MD?

866 Diamond Dr, Gaithersburg, MD is assigned to Diamond Elementary School (elementary), rated A; Lakelands Park Middle School (middle), rated B-; Northwest High School (high), rated B+. All sit in Montgomery County Public Schools. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 866 Diamond Dr, Gaithersburg, MD compare to other homes in Gaithersburg 20878?

Among the 20,757 homes in Gaithersburg 20878, it is worth more than 43% of them ($690,941 against a typical $740,407), its price per square foot is higher than 59% of them ($320 against a typical $308), it is bigger than 47% of them (2,156 ft² against a typical 2,268 ft²), its lot is bigger than 62% of them (0.21 ac against a typical 0.11 ac) and it is newer than 10% of them (1971 against a typical 1988). Measured against all of Montgomery County, it is worth more than 58% 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 866 Diamond Dr, Gaithersburg, MD?

The 2025 property tax bill for 866 Diamond Dr, Gaithersburg, MD was $6,377. The county assessed it at $550,300.

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