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Single Family ResidenceResidential
$5,100,975$2,074 / 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 83How 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 RITTENHOUSE AVE

ATHERTON, CA 94027
4
Beds
3
Baths
2,460 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.
0.32 ac
Lot SizeThe size of the land the home sits on, from county records.
1940
Year BuiltThe year the home was originally built, according to county records.
8
RoomsThe total room count in county records. Counties differ on which rooms they count, so compare it loosely.
2
ParkingThe number of parking spaces on the property, including the garage.

Valuation

$5.1M
$4.3M low$5.9M high

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$13,078 (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.$1,109,338 (2026)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$554,669
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$554,669
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$1,087,588
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$4,065,210

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.7 in
30-Year Flood ChanceThe chance of at least one serious flood here in the next 30 years, not in any single year.30%
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.minimal

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.Ranch
CountySAN MATEO
Lot (acres)The size of the land the home sits on, from county records.0.32
RoofThe main material covering the roof, such as asphalt shingle or tile.Wood
HeatingThe type of heating system in the home.Central
CoolingThe type of cooling or air conditioning in the home.Central
FireplaceWhether the home has a fireplace, and what kind.Yes
PoolWhether the property has a pool, and what kind, such as in-ground.No

Transaction History(5)

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
Garfield Elementary SchoolB-
Elementary · Grades KG–8 · 0.3 mi
H
Menlo-Atherton High SchoolA-
High · Grades 9–12 · 1.6 mi

District: Redwood City Elementary School District

Neighborhood · ZIP 94027These 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.98
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.93
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.511

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.87%
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.4.5%
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.7,126
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.1,411 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$294,375
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$482,221
Average tempThe average temperature here across a full year.59°F
Annual precipHow much rain and melted snow falls here in a typical year.20 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.66%

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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 Rittenhouse 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 more than 97% of homes in San Mateo County
  • Costs more per square foot than 98% of homes in San Mateo County
  • Smaller than 81% of homes in Atherton 94027
  • Has a smaller lot than 90% of homes in Atherton 94027
  • Older than 89% of homes in Lloyden Park

What homes are worth in Atherton 94027

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

This home
$1.3M$9M

This home is worth more than 32% of homes in Atherton 94027.

How it measures up in Atherton 94027

The dot is this home. The mark in the middle is the typical home in Atherton 94027.

Estimated value$5,100,975
CheaperTypical $6,402,361Pricier

Pricier than 32% of homes nearby

Price per ft²$2074
CheaperTypical $2169Pricier

Pricier than 42% of homes nearby

Living area2,460 ft²
SmallerTypical 3,930 ft²Bigger

Bigger than 19% of homes nearby

Lot size0.32 ac
SmallerTypical 1 acBigger

Bigger than 10% of homes nearby

Year built1940
OlderTypical 1958Newer

Newer than 15% of homes nearby

How 21 Rittenhouse Ave ranks against every home in each area.
MeasureThis homeLloyden ParkAtherton 94027San Mateo County
Estimated valuepricier than$5,100,97572% of homes32% of homes97% of homes
Price per ft²pricier than$207474% of homes42% of homes98% of homes
Living areabigger than2,460 ft²57% of homes19% of homes81% of homes
Lot sizebigger than0.32 ac33% of homes10% of homes79% of homes
Year builtnewer than194011% of homes15% of homes12% of homes

About 21 Rittenhouse Ave

How much is 21 Rittenhouse Ave, Atherton, CA worth?

The TopHap Estimate for 21 Rittenhouse Ave, Atherton, CA is $5,100,975 as of Jul 14, 2026. The likely range is $4,255,956 to $5,945,994. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 21 Rittenhouse Ave, Atherton, CA last sell?

21 Rittenhouse Ave, Atherton, CA last sold on Mar 2, 1995, according to the county's recorded deed. TopHap holds 3 recorded sales for this parcel.

How big is 21 Rittenhouse Ave, Atherton, CA?

21 Rittenhouse Ave, Atherton, CA has 4 bedrooms, 3 bathrooms, 2,460 square feet of living space and a 0.32-acre lot.

When was 21 Rittenhouse Ave, Atherton, CA built?

21 Rittenhouse Ave, Atherton, CA was built in 1940, making it 86 years old. It is a ranch home.

What schools serve 21 Rittenhouse Ave, Atherton, CA?

21 Rittenhouse Ave, Atherton, CA is assigned to Garfield Elementary School (elementary), rated B-; Menlo-Atherton High School (high), rated A-. All sit in Redwood City Elementary School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 21 Rittenhouse Ave, Atherton, CA compare to other homes in Atherton 94027?

Among the 2,582 homes in Atherton 94027, it is worth more than 32% of them ($5,100,975 against a typical $6,402,361), its price per square foot is higher than 42% of them ($2074 against a typical $2169), it is bigger than 19% of them (2,460 ft² against a typical 3,930 ft²), its lot is bigger than 10% of them (0.32 ac against a typical 1 ac) and it is newer than 15% of them (1940 against a typical 1958). Measured against all of San Mateo County, it is worth more than 97% 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 Rittenhouse Ave, Atherton, CA?

The 2025 property tax bill for 21 Rittenhouse Ave, Atherton, CA was $13,078. The county assessed it at $1,109,338.

More homes on Rittenhouse Ave

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Assigned schools

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