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Single Family ResidenceResidential
$1,255,969$498 / 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 93How 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

551 TOPSIDE PL

DIAMOND BAR, CA 91765
3
Beds
3
Baths
2,524 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.
0.19 ac
Lot SizeThe size of the land the home sits on, from county records.
1988
Year BuiltThe year the home was originally built, according to county records.

Valuation

$1.3M
$1.2M low$1.3M high

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$7,160 (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.$511,171 (2026)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$119,074
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$392,097
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$501,149

Property Facts

Property TypeThe broad category the county puts this property in, such as residential or commercial.Single Family Residence
CountyLOS ANGELES
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.1995
Lot (acres)The size of the land the home sits on, from county records.0.19
ConstructionThe main material the home's frame and walls are built from.Wood (Unspecified)
HeatingThe type of heating system in the home.Central
CoolingThe type of cooling or air conditioning in the home.Central
PoolWhether the property has a pool, and what kind, such as in-ground.Yes

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.

H
Diamond Ranch High SchoolA-
High · Grades 9–12 · 0.6 mi
E
Pantera Elementary SchoolA+
Elementary · Grades KG–6 · 0.6 mi
M
Lorbeer Middle SchoolC+
Middle · Grades 7–8 · 1.1 mi

District: Pomona Unified School District

Neighborhood · ZIP 91765These 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.46
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.101
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.388

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.35%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.9.2%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.1.7%
PopulationHow many people live in this area.41,302
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.2,738 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$98,979
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$125,933
Average tempThe average temperature here across a full year.63°F
Annual precipHow much rain and melted snow falls here in a typical year.19 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.73%

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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

551 Topside Pl 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 77% of homes in Los Angeles County
  • Costs less per square foot than 70% of homes in Diamond Bar 91765
  • Bigger than 82% of homes in Los Angeles County
  • Has a smaller lot than 73% of homes in Diamond Bar 91765
  • Newer than 90% of homes in Diamond Bar 91765

What homes are worth in Diamond Bar 91765

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

This home
$340K$3.2M

This home is worth more than 75% of homes in Diamond Bar 91765.

How it measures up in Diamond Bar 91765

The dot is this home. The mark in the middle is the typical home in Diamond Bar 91765.

Estimated value$1,255,969
CheaperTypical $986,221Pricier

Pricier than 75% of homes nearby

Price per ft²$498
CheaperTypical $536Pricier

Pricier than 30% of homes nearby

Living area2,524 ft²
SmallerTypical 1,822 ft²Bigger

Bigger than 80% of homes nearby

Lot size0.19 ac
SmallerTypical 0.25 acBigger

Bigger than 27% of homes nearby

Year built1988
OlderTypical 1979Newer

Newer than 90% of homes nearby

How 551 Topside Pl ranks against every home in each area.
MeasureThis homeDiamond Bar 91765Los Angeles County
Estimated valuepricier than$1,255,96975% of homes77% of homes
Price per ft²pricier than$49830% of homes35% of homes
Living areabigger than2,524 ft²80% of homes82% of homes
Lot sizebigger than0.19 ac27% of homes62% of homes
Year builtnewer than198890% of homes85% of homes

About 551 Topside Pl

How much is 551 Topside Pl, Diamond Bar, CA worth?

The TopHap Estimate for 551 Topside Pl, Diamond Bar, CA is $1,255,969 as of Aug 30, 2026. The likely range is $1,173,225 to $1,338,713. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 551 Topside Pl, Diamond Bar, CA last sell?

551 Topside Pl, Diamond Bar, CA last sold on Jan 1, 1900, according to the county's recorded deed.

How big is 551 Topside Pl, Diamond Bar, CA?

551 Topside Pl, Diamond Bar, CA has 3 bedrooms, 3 bathrooms, 2,524 square feet of living space and a 0.19-acre lot.

When was 551 Topside Pl, Diamond Bar, CA built?

551 Topside Pl, Diamond Bar, CA was built in 1988, making it 38 years old.

What schools serve 551 Topside Pl, Diamond Bar, CA?

551 Topside Pl, Diamond Bar, CA is assigned to Diamond Ranch High School (high), rated A-; Pantera Elementary School (elementary), rated A+; Lorbeer Middle School (middle), rated C+. All sit in Pomona Unified School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 551 Topside Pl, Diamond Bar, CA compare to other homes in Diamond Bar 91765?

Among the 15,284 homes in Diamond Bar 91765, it is worth more than 75% of them ($1,255,969 against a typical $986,221), its price per square foot is higher than 30% of them ($498 against a typical $536), it is bigger than 80% of them (2,524 ft² against a typical 1,822 ft²), its lot is bigger than 27% of them (0.19 ac against a typical 0.25 ac) and it is newer than 90% of them (1988 against a typical 1979). Measured against all of Los Angeles County, it is worth more than 77% 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 551 Topside Pl, Diamond Bar, CA?

The 2025 property tax bill for 551 Topside Pl, Diamond Bar, CA was $7,160. The county assessed it at $511,171.

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