Episode 2 · Property Types & Supply Dynamics
San Mateo Houses: Size, Age, Ownership and Taxes
San Mateo is a city of single-family streets that were mostly built in one short stretch of the last century. This guide describes those houses: how big they are, how old they are, how long owners keep them and what they cost to hold. It covers single-family homes only, not buildings with shared walls.
đź’ˇ Key Insights & Takeaways
- The median single-family house in San Mateo has 1,608 square feet of living area, and the median lot is 5,805 square feet.
- Houses are mostly one story, at 81.3%, and three bedrooms with two bathrooms is the most common pairing, at 32.9% of houses.
- Parcels last sold 20 or more years ago are assessed at 52.7% of the level of those sold under 3 years ago, and their median tax bill is 58.5% as large.
- Trusts and estates hold 20.3% of single-family parcels, while companies and LLCs hold 1.2%.
- Between 16.4% and 23.0% of single-family houses pass at least three of five tests for rebuilding, and that range is a ceiling, not a count of houses to be torn down.
As of 20 October 2026, 65.2% of San Mateo single-family houses with a recorded year built went up in just two decades, 1940 to 1959, and they are the smaller houses, with a median living area of 1,480 square feet. The houses built before 1940 are bigger, at a median of 1,751 square feet.
At a glance
Single-family houses in San Mateo, as of 20 October 2026.
| Measure | Value | As of |
|---|---|---|
| Single-family parcels | 19,180 | 20 October 2026 |
| Median living area | 1,608 square feet | 20 October 2026 |
| Median year built | 1950 | 20 October 2026 |
| Median hold, parcels with a sale date (a floor) | 14.6 years | 20 October 2026 |
| Median annual property tax bill | $12,363 | 20 October 2026 |
How many single-family houses does San Mateo have?
This guide covers single-family homes only. It leaves out condominiums, townhomes, apartments and commercial buildings. The data has no class for them, so a city-wide split between house types cannot be drawn.
As of 20 October 2026, San Mateo has 19,180 single-family parcels. A parcel is one lot of land, so this is a count of lots, not of every property, home or housing unit in the city. Of those parcels, 568 are marked as having a second small home on the lot, called an accessory dwelling, and that is 3.0% of the total.
Two groups of entries are left out of the 19,180. The data holds 8,696 entries that give an address and nothing else about the property, and counting them would have overstated the number of parcels by 39.6%. Another 2,772 entries list a lot size and no land use, so they are not counted as homes.
Most houses have one story. A total of 81.3% have one story and 18.7% have two or more. The median house has 3 bedrooms and 2 bathrooms, and three bedrooms with two bathrooms is the most common pairing, at 32.9% of houses. One bathroom is the count for 20.3% of houses, and three or more bathrooms is the count for 33.3%.
How big are San Mateo's houses and lots?
As of 20 October 2026, across all 19,180 single-family parcels, the median house has 1,608 square feet of living area and the median lot is 5,805 square feet. A floor-area ratio is living area divided by lot area, and the median here is 0.258.
The size of the median house changes with the postal area. ZIP codes are mail lines, not neighborhoods, so the table compares mail areas and nothing more. The houses are largest in 94402 and smallest in 94401.
Median living area of single-family houses by ZIP code, as of 20 October 2026 (19,173 parcels with a ZIP code and a recorded living area).
| ZIP code | Median living area (square feet) |
|---|---|
| 94401 | 1,270 |
| 94402 | 1,870 |
| 94403 | 1,550 |
| 94404 | 1,660 |
Are San Mateo's older houses smaller?
As of 20 October 2026, the median single-family house in San Mateo was built in 1950, and 44.1% were built before 1950. Only 1.6% were built in 2000 or later. A total of 65.2% were built in the two decades from 1940 to 1959.
Older does not mean smaller here. The 3,190 houses built before 1940 have a median living area of 1,751 square feet, against 1,480 square feet for the 12,495 houses built from 1940 to 1959. Bathrooms follow the same pattern. If you want three bathrooms or more floor area on a lot of this size, the houses built before 1940 are where both show up more often.
Size and bathrooms of single-family houses by era of construction, as of 20 October 2026.
| Measure | Built before 1940 | Built 1940 to 1959 |
|---|---|---|
| Houses counted (n) | 3,190 | 12,495 |
| Median living area | 1,751 square feet | 1,480 square feet |
| Share with three or more bathrooms | 42.0% | 21.4% |
This guide cannot say how many houses have been renovated. The year of the last update is blank on 33.5% of parcels, so any renovation share would be a guess. The counts also show each house as it is recorded today, and they do not show whether an older house was enlarged.
How long do owners keep San Mateo houses?
Among the 14,162 single-family parcels with a recorded sale date, the median hold is 14.6 years as of 20 October 2026. Of those, 36.3% have been held for 20 years or more and 12.6% for 30 years or more. A sale has been recorded since 30 September 2024 on 7.0% of them, which is a share of parcels and not a count of sales.
Every tenure figure here is a floor. A sale date is recorded for 73.8% of single-family parcels, and the other 26.2% have no date. Those undated parcels may include original owners and very long holds, so the true share of long holds is higher than the dated parcels show. The latest recorded sale in the data is from 13 July 2026, so the figures are understated by at most that gap.
Trusts and estates hold 20.3% of single-family parcels, and companies and LLCs hold 1.2%. Any kind of entity on the owner line, a floor, covers 21.5%. A trust is an estate-planning tool common among owners who stay a long time, so this guide does not read a trust as a sign that a house is held for rent or resale. 69.9% of parcels list a second owner.
Whether an owner lives in the house cannot be measured, because the data carries no homeowners' exemption field. The 1.2% held by companies and LLCs is the closest stand-in for houses held as a business.
What does it cost to hold a San Mateo house?
California's Proposition 13 limits a rise in assessed value to 2% a year and resets the assessment when a house changes owners. Assessed value is the county's estimate for tax purposes. It is not market value, and it is not what a house would sell for.
As of 20 October 2026, the median assessed value of a San Mateo single-family house is $897,189, and the median annual property tax bill is $12,363. The median effective tax rate is 1.36%, which is the tax billed divided by the assessed value. That sits above the 1.10% to 1.30% range expected in California, and 64.3% of parcels are above 1.30%. The bill is not itemized, so this guide cannot say which levies push the rate up. The rate is also not a forecast of the bill you would pay, because your bill follows the price you pay.
The cap shows in the gap between long-time and recent owners. Parcels last sold 20 or more years ago have a median assessed value that is 52.7% of the median for parcels sold under 3 years ago, yet their median tax bill is 58.5% as large. Comparing two assessments tells you more about the year each house was bought than about what each is worth today.
The median assessed value is 1.28x the last recorded sale amount, and the gap is widest for the oldest sales. Of parcels with a recorded sale amount, 7.9% are assessed at twice that amount or more, and 9.0% are assessed below it. This measures the tax lock, not price growth. The data has no code to separate family transfers at a nominal price, so some of those remain in the base.
Median assessed value as a multiple of the last recorded sale amount, by decade of that sale, as of 20 October 2026.
| Decade of last recorded sale | Assessed value over sale amount | Parcels counted (n) |
|---|---|---|
| 1980s | 1.99x | 1,020 |
| 2000s | 1.42x | 3,512 |
| 2020s | 1.02x | 3,509 |
| All dated sales | 1.28x | 13,774 |
The county does not split an assessed value into land and building, so there is no land share to report. This guide uses a Structure Share Proxy instead, which means measures of how heavily lots are built on. The median assessed value is $569 per living square foot and $146 per lot square foot, and the median house's living area is 0.277 of the median lot's area. These are assessment measures, not market prices per square foot, and they are not a land-versus-building split.
How many San Mateo houses could be redeveloped?
This data cannot say how many houses will be rebuilt, but a screen can set a ceiling. A house is a strong candidate when it meets three or more of five conditions. It covers little of its lot, it has a high assessed value per square foot of lot, it has a high assessed value per square foot of living area, it shows no sign of renovation, and it was built before 1950.
As of 20 October 2026, 4,415 single-family parcels, or 23.0%, are strong candidates, and 5,759 more meet two conditions. The 23.0% is an upper bound. The year of the last update is blank on 33.5% of parcels, and the screen counts a blank as no renovation. If a blank does not count, the strong share falls to 16.4%.
Two more limits apply. Assessed values reflect the year of purchase, so houses bought recently score higher on two of the conditions. No zoning data was available, so the screen cannot test what the city allows to be built. Read the range from 16.4% to 23.0% as a ceiling on how many houses are candidates, not as a count of houses to be torn down.
Common questions
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