Episode 2 · Property Types & Supply Dynamics
Atherton Housing: House Size, Lots, Age, Assessments
Atherton is known as a town of large houses on large lots. This guide shows how big those houses and lots are, how old the houses are, how they are assessed and taxed, and how long owners keep them. It also shows how much of the town these records describe, because that shapes how far each figure reaches.
đź’ˇ Key Insights & Takeaways
- Of the single-family parcels with a property record, 88.9% have 4,000 square feet of living space or more, and 54.9% sit on a lot of one acre or more.
- The median house was built in 2010, but the 85.1% built in 2000 or later reflects a subset that leans toward recent construction, not the whole town.
- The median annual property tax is $116,399, a median effective rate of 1.115% of assessed value, and assessed value is not market value.
- The median parcel last changed hands 11.2 years ago, and 54.0% have gone 10 years or more, though hold times run short.
- Where assessed value is at least twice the last recorded sale, 92.8% of parcels have a house built after that sale, so rebuilds explain the wide gaps.
If you are weighing an Atherton house, size is the first figure to check: as of 15 October 2026, the median single-family parcel with a property record holds 6,947 square feet of living space on a 43,584-square-foot lot. Those records cover only 29.7% of the town's parcels, so read them as a subset.
Atherton housing at a glance, as of 15 October 2026.
| Measure | Value | Basis |
|---|---|---|
| Parcels in Atherton | 2,402 | Parcels, not homes; 1,688 of them carry no property description |
| Single-family parcels with a property record | 712 | 29.7% of the parcels carry a record, so each figure below describes a subset |
| Median living space | 6,947 square feet | The county's measure; n = 712 |
| Median lot | 43,584 square feet | n = 712 |
| Median annual property tax | $116,399 | Tax on assessed value, which is not market value; n = 712 |
How much of Atherton do these figures describe?
They describe a subset of the town. As of 15 October 2026, the county gives a full property description for 29.7% of the 2,402 parcels in Atherton, and 712 of those are single-family parcels. A parcel is one piece of land on the county's map, so 2,402 counts parcels and not homes or households.
The other 1,688 parcels carry no property description. They are not vacant land. The county lists them with a lot size or an address and nothing else. The parcels that do carry a description lean toward homes that have been listed for sale. Every figure below describes those 712 single-family parcels and not every house in Atherton. A median here means that half of the 712 sit above the figure and half below it.
How big are Atherton houses, and how much lot comes with them?
The median single-family parcel with a property record holds 6,947 square feet of living space on a 43,584-square-foot lot, as of 15 October 2026. Living space is the county's measure. It differs from the size on a listing by more than 20% on 41.2% of the homes where both are known, so do not match the two house by house.
Atherton single-family parcels with a property record, size and layout, as of 15 October 2026 (n = 712).
| Measure | Value | Basis |
|---|---|---|
| Median living space | 6,947 square feet | The county's measure |
| Median lot | 43,584 square feet | Lot area |
| Share with 4,000 square feet of living space or more | 88.9% | Of 712 parcels |
| Share on a lot of one acre or more | 54.9% | Of 712 parcels |
| Median floor-area ratio | 0.168 | Living space divided by lot area; about one-sixth |
| Median bedrooms | 5 | The county's count |
| Median bathrooms | 6.0 | The county's count |
The lots in this subset look like the rest of the town. The median lot is 42,240 square feet across the 2,209 parcels that carry any lot area, against 43,584 square feet for the single-family parcels with a record.
How old are Atherton houses, and have they been renovated?
The median single-family parcel with a property record has a house built in 2010, as of 15 October 2026 (n = 711). Only 1.3% were built before 1950, and 85.1% were built in 2000 or later. That age profile leans toward recent construction because the parcels with a description lean toward listed homes. It does not show that Atherton is a town of new houses.
The county also dates the last major work on some houses, which it calls the effective year built. Among the 339 parcels that carry one, 12.4% show a gap between the year built and that effective year, which points to a renovation. The effective year is blank on 52.3% of the records that carry a year built, so the 12.4% describes only the parcels that carry one and says nothing about the rest.
What do Atherton houses cost to hold in property tax?
Assessed value is the county's figure for tax, and it is not market value. Proposition 13 in California limits the yearly rise in assessed value to 2% and resets the base value when a house changes owners or new construction is added. A parcel bought in one year and a parcel bought in another can carry very different assessed values for that reason, so compare them with care.
Atherton single-family parcels with a property record, assessed value and property tax, as of 15 October 2026 (n = 712).
| Measure | Value | Basis |
|---|---|---|
| Median assessed value | $10,404,220 | The county's figure, not a sale price |
| Median annual property tax | $116,399 | Tax billed on assessed value |
| Median effective tax rate | 1.115% | Annual tax divided by assessed value |
| Share with an effective rate from 1.10% to 1.30% | 95.4% | Of 712 parcels |
| Median assessed value per living square foot | $1,481 | An assessment figure, not a price per square foot |
The county does not split land from buildings, so the $1,481 figure cannot tell you how much of the assessed value is land.
How long do owners keep Atherton houses?
The median parcel last changed hands 11.2 years before 15 October 2026, and 54.0% have gone 10 years or more without a recorded sale (n = 669 parcels with a recorded sale date). These hold times run short. The latest recorded transfer is dated 26 May 2026, so any later sale is not counted, and the years are understated by about that gap. The data does not say who owns a parcel or whether the owner lives in the house.
Why do Atherton assessed values sit so far above the last recorded sale?
Rebuilds explain the gap better than long holds do. The median parcel is assessed at 1.26 times its last recorded sale, and 30.7% are assessed at twice that sale or more (n = 635). Among the parcels at twice or more, 92.8% have a house built after the last recorded sale (n = 195). Where the house is older than the last sale, the median is 1.09 times and 3.5% reach twice (n = 401).
Across the 634 parcels with every field filled in, 36.8% have a house built after the last recorded sale. The ratio mixes two effects, the 2% yearly rise and new construction added since the sale. For that reason it does not measure the Proposition 13 limit alone. These are assessed values and not market values.
The same data feed a screen for houses that could be rebuilt. It flags up to 151 parcels, 21.2% of the 712, as strong redevelopment candidates. That is a ceiling and not a count of expected teardowns. The effective year built is blank on 52.3% of records that carry a year built, and a blank reads as no recent work.
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