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Single Family ResidenceResidential
$836,204$674 / 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 97How well the pricing models agreed with each other on this home. Higher means the estimate rests on stronger, more consistent data.· as of Oct 21, 2026
Last sold for $575,000 on Jul 21, 2006

4277 GEM AVE

CASTRO VALLEY, CA 94546
3
Beds
2
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.
0.13 ac
Lot SizeThe size of the land the home sits on, from county records.
1947
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.
1
ParkingThe number of parking spaces on the property, including the garage.

Valuation

$836K
$812K low$861K high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$575,000 · Jul 21, 2006

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$10,454 (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.$828,611 (2026)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$235,716
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$599,895
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$812,228
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$839,160

Property Facts

Property TypeThe broad category the county puts this property in, such as residential or commercial.Single Family Residence
CountyALAMEDA
Lot (acres)The size of the land the home sits on, from county records.0.13
ConstructionThe main material the home's frame and walls are built from.Wood (Unspecified)
PoolWhether the property has a pool, and what kind, such as in-ground.No

Transaction History(3)

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
Marshall Elementary SchoolA
Elementary · Grades KG–5 · 0.2 mi
M
Creekside Middle SchoolA
Middle · Grades 6–8 · 0.2 mi
H
Castro Valley High SchoolA-
High · Grades 9–12 · 0.8 mi

District: Castro Valley Unified School District

Neighborhood · ZIP 94546These 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.78
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.91
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.657

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.27%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.8.9%
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.46,776
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.4,466 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$117,352
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$142,642
Average tempThe average temperature here across a full year.57°F
Annual precipHow much rain and melted snow falls here in a typical year.23 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.78%

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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

4277 Gem Ave 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 77% of homes in Castro Valley
  • Costs more per square foot than 67% of homes in Castro Valley
  • Smaller than 81% of homes in Castro Valley
  • Has a smaller lot than 66% of homes in Castro Valley 94546
  • Older than 88% of homes in Castro Valley

What homes are worth in Castro Valley 94546

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

This home
$443K$1.8M

This home is worth more than 29% of homes in Castro Valley 94546.

How it measures up in Castro Valley 94546

The dot is this home. The mark in the middle is the typical home in Castro Valley 94546.

Estimated value$836,204
CheaperTypical $988,225Pricier

Pricier than 29% of homes nearby

Price per ft²$674
CheaperTypical $629Pricier

Pricier than 65% of homes nearby

Living area1,240 ft²
SmallerTypical 1,547 ft²Bigger

Bigger than 26% of homes nearby

Lot size0.13 ac
SmallerTypical 0.15 acBigger

Bigger than 34% of homes nearby

Year built1947
OlderTypical 1955Newer

Newer than 14% of homes nearby

How 4277 Gem Ave ranks against every home in each area.
MeasureThis homeCastro ValleyCastro Valley 94546Alameda County
Estimated valuepricier than$836,20423% of homes29% of homes35% of homes
Price per ft²pricier than$67467% of homes65% of homes54% of homes
Living areabigger than1,240 ft²19% of homes26% of homes28% of homes
Lot sizebigger than0.13 ac37% of homes34% of homes46% of homes
Year builtnewer than194712% of homes14% of homes28% of homes

About 4277 Gem Ave

How much is 4277 Gem Ave, Castro Valley, CA worth?

The TopHap Estimate for 4277 Gem Ave, Castro Valley, CA is $836,204 as of Oct 21, 2026. The likely range is $811,691 to $860,717. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 4277 Gem Ave, Castro Valley, CA last sell?

4277 Gem Ave, Castro Valley, CA last sold on Jul 21, 2006 for $575,000, according to the county's recorded deed. TopHap holds 2 recorded sales for this parcel.

How big is 4277 Gem Ave, Castro Valley, CA?

4277 Gem Ave, Castro Valley, CA has 3 bedrooms, 2 bathrooms, 1,240 square feet of living space and a 0.13-acre lot.

When was 4277 Gem Ave, Castro Valley, CA built?

4277 Gem Ave, Castro Valley, CA was built in 1947, making it 79 years old. The building has 1 story.

What schools serve 4277 Gem Ave, Castro Valley, CA?

4277 Gem Ave, Castro Valley, CA is assigned to Marshall Elementary School (elementary), rated A; Creekside Middle School (middle), rated A; Castro Valley High School (high), rated A-. All sit in Castro Valley Unified School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 4277 Gem Ave, Castro Valley, CA compare to other homes in Castro Valley 94546?

Among the 13,490 homes in Castro Valley 94546, it is worth more than 29% of them ($836,204 against a typical $988,225), its price per square foot is higher than 65% of them ($674 against a typical $629), it is bigger than 26% of them (1,240 ft² against a typical 1,547 ft²), its lot is bigger than 34% of them (0.13 ac against a typical 0.15 ac) and it is newer than 14% of them (1947 against a typical 1955). Measured against all of Alameda County, it is worth more than 35% 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 4277 Gem Ave, Castro Valley, CA?

The 2025 property tax bill for 4277 Gem Ave, Castro Valley, CA was $10,454. The county assessed it at $828,611.

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