A Belmont applicant once wanted to add 38 square feet to a closet. As the San Mateo Daily Journal reported, city staff described how the property sat in a planned development district. That meant the closet needed a conditional use permit and a Planning Commission hearing. Senior Planner Rob Gill told the City Council that the applicant "had to go through this process and wait to get on a Planning Commission hearing" and paid extra application costs on top of that.
That closet helps explain a pattern in the sales data. Belmont and its neighbor San Carlos sell single-family homes at nearly the same median price. Belmont's price per square foot has been lower in every monthly report from April through August 2025 and April through September 2026. If you're comparing the two cities, that gap tells you more than the median does. Part of it reflects ground that is steep, slow or costly to build on.
Eleven monthly comparisons, and San Carlos is higher every time
The San Mateo County Association of Realtors publishes monthly single-family figures by city, compiled by MLSListings. Here is the median price per square foot for each city from April through September 2026, with the same months of 2025 where available.
| Month | Belmont $/sq ft | San Carlos $/sq ft | Gap |
|---|---|---|---|
| April 2025 | $1,366 | $1,487 | $121 |
| May 2025 | $1,231 | $1,437 | $206 |
| June 2025 | $1,298 | $1,399 | $101 |
| July 2025 | $1,238 | $1,361 | $123 |
| August 2025 | $1,133 | $1,323 | $190 |
| April 2026 | $1,359 | $1,437 | $78 |
| May 2026 | $1,365 | $1,466 | $101 |
| June 2026 | $1,349 | $1,579 | $230 |
| July 2026 | $1,281 | $1,394 | $113 |
| August 2026 | $1,302 | $1,445 | $143 |
| September 2026 | $1,261 | $1,604 | $343 |
Each city sells only a couple dozen homes a month, so any single row is noisy. Even so, the gap never once flips. The median sale price is a different story. Belmont's median beat San Carlos's in April 2025 at $2,615,000 against $2,612,500, in August 2025 at $2,250,000 against $2,200,000, and in August 2026 at $2,667,500 against $2,500,000. In the other months San Carlos came out ahead. A figure that changes direction from month to month can't guide an offer.
What a September 2026 budget buys at each city's rate
The latest figures cover September 2026, released by SAMCAR on October 9. Belmont closed 21 single-family sales at a median of $2,715,000. Homes went for 105% of list price on average and spent an average of 26 days on market. San Carlos closed 19 sales at a median of $2,750,000, with 108% of list price received.
So the medians were $35,000 apart, but the per-square-foot figures were $343 apart. That puts San Carlos about 27% higher than Belmont that month. Run a $2.7 million budget through each city's September median and you get roughly 2,140 square feet at Belmont's rate and about 1,680 at San Carlos's. That's simple division, not a promise about any particular listing. Still, it shows how far apart the two cities can be on the measure that matters once you're inside the house.
Bidding pressure matched the pricing. In September 2026, SAMCAR put Belmont at 1.1 months to sell its inventory and San Carlos at 0.8. A year earlier, Belmont homes sold for 102% of list, and that rose to 105% this September. Belmont isn't cheap. Buyers are competing there too, just at a lower price per foot.
One caution about reading these numbers. SAMCAR's average home size and lot size don't always favor Belmont. Belmont's average sold home was larger than San Carlos's in only two of the five months from April through August 2026. The lower price per foot doesn't mean Belmont homes are reliably bigger. The cause lies in the land the homes sit on.
Where the discount comes from
The City of Belmont's Hillside Development in Belmont page has a section for buyers headed "Know Before You Buy." It covers the San Juan Hills and Western Hills areas and warns that some properties there "are advertised as developable but may face significant restrictions or challenges" because of:
- Steep slopes
- Geological hazards
- Limited access and infrastructure
- Environmental protections
- Zoning and General Plan policies
The same city page says many parcels in those two areas are subject to California's Certificate of Compliance review. That's the city's determination that a parcel was legally created under the Subdivision Map Act. If a parcel lacks a recorded legal history, it may not count as a separate legal lot for development. Depending on location, building there can also mean extending a road, widening pavement, building a driveway and adding roadside drainage. The details are in the San Juan Hills Area Plan and Western Hills Area Plan.
The city's hillside page also says plainly what it sees happen:
"Each year, the City encounters cases where buyers unknowingly purchase land expecting to build, only to find their parcel is undevelopable or requires costly and lengthy permitting processes."
That cost lands on the buyer, and prices reflect it. A square foot on a slope with a long permitting path is worth less to the next buyer than a square foot on a flat lot that's easy to expand. Belmont's history fits that picture. Russ Estep, writing as Belmont's city historian in columns collected by the Belmont Historical Society, described local homes as upslope houses with many steps and downslope lots with steps down to the front door. Belmont's flat subdivisions came from repurposed open land. Estep wrote that Sterling Downs was built on the former Belmont Airport site and that a dog-racing track had been located near where Homeview was built. The Belmont Country Club subdivisions were being sold between 1924 and 1927. In San Carlos, the city's own history highlights Spanish-style cottages in the flat area south of San Carlos Avenue, typical of 1920s architecture.
The rule change aimed at adding space
Slope is only part of it. The closet story points to a second cost, which is the process of making an existing house bigger. Belmont is now working on that.
The city is considering updates to the rules for residential additions, the Planned Development review process and San Carlos Airport safety zones, guided by a City Council Housing and Long-Range Planning Subcommittee formed in early 2026. At the Council's June 23 meeting, staff presented the amendments for initial feedback, and the Council directed staff to draft formal ordinances for later Planning Commission and Council review.
The Daily Journal's coverage laid out the proposal:
| Item | Current process, as reported | Proposed |
|---|---|---|
| Ground-floor additions | Director approval up to 399 sq ft | Director approval up to 500 sq ft |
| Larger additions | Some require Planning Commission approval | Zoning administrator approval of any size if objective standards like setbacks, height and floor-area ratio are met |
| New single-family homes | Planning Commission review | Planning Commission review stays |
| Planned development zoning | Separate rules | Aligned with other residential zoning |
Councilmember Tom McCune explained the reasoning in the same Daily Journal report: "Anytime a project goes to the Planning Commission, it creates an additional delay, it creates an additional level of uncertainty for the applicant." As of this writing, the city's zoning amendments page still lists Planning Commission and Council review as future steps. These are proposals, not adopted rules. If they pass, a flat-lot Belmont house with room to grow would face less of the process cost that may be built into today's price per foot. Hillside constraints are a separate matter and wouldn't change.
Checking a Belmont listing against the discount
The city's hillside page gives buyers a short checklist. It's useful anywhere in Belmont where you're paying partly for future potential:
- Look up the parcel in the city's Parcel Viewer and read the applicable area plan.
- Research the property's history, including past applications.
- Confirm access, utilities and grading limits.
- Talk with city planning staff before you buy. The city lists [email protected] and 650-595-7417.
- Bring in a licensed civil engineer or geotechnical consultant where slope is involved.
A Belmont home priced near the city's median per foot may have that price for a reason that shows up in these steps. One priced well above it may be a flat, easy-to-expand property where the usual discount doesn't apply.
Quick answers
Is Belmont cheaper than San Carlos? At the median sale price, not reliably. The lead changed hands several times across 2025 and 2026. On price per square foot, Belmont was lower in every month SAMCAR reported from April through September 2026, and in April through August 2025.
Do Belmont buyers get bigger homes? Not consistently. Average home size and lot size go back and forth between the two cities from month to month. The steady difference is the price per foot.
Are Belmont's addition rules changing? They're proposed, not adopted. As of the city's page, draft amendments are waiting on Planning Commission and Council review.
This post is general information, not legal or financial advice. Confirm any parcel, permit or zoning question with the City of Belmont and the right licensed professional.
If you're weighing a Belmont listing against one in San Carlos, Luis Vasquez can go through the per-square-foot comps, parcel history and expansion potential with you before you write an offer, in English or Spanish. Get your free Buying & Selling Guide and schedule a market consultation.
