In Los Altos Hills, the Acre and the Square Footage Are Two Different Purchases

In August 2026, the Los Altos Hills Pathways Committee took up a routine-sounding item: a homeowner at 12020 Greenhills Court had asked to move a trail easement that crossed their property. The committee said no. The existing alignment stayed, because it was safer and more accessible for the bikes and horses that use it. The homeowner owned the acre. They did not own the right to decide where the path across it would go.

That decision is a small thing on its own, but it is a clean example of something buyers in this market consistently misjudge: in Los Altos Hills, the acre you close on and the house you can build on it are governed by two separate sets of rules, and neither one is fully in your hands. Most people shopping this town compare it to its neighbors on price per square foot, the way you'd compare any two ZIP codes. That comparison is quietly misleading here, and understanding why changes how you should read a listing before you write an offer.

The Acre on the Deed Isn't the Acre You Can Build On

Los Altos Hills requires a minimum net lot area of one acre, a rule the town has held since incorporating in 1956 specifically to preserve a rural, low-density character. But acreage alone doesn't tell you how much house you're allowed to put on that acre. The town runs a separate calculation, tied to the average slope of the parcel, called the Maximum Development Area formula.

At the shallowest slope tier, the code allows up to 15,000 square feet of development area on a qualifying lot. At the steepest tier, that number compresses to a floor of 7,500 square feet, half as much, on a parcel that can carry the exact same one-acre designation on paper. The town's own published worksheet walks through a representative case: a one-acre lot with an average slope of 14 percent, no special landscape area, and no conservation constraints computes out to 12,339 square feet of maximum development area. That's the arithmetic the planning department actually runs, lot by lot, before anyone talks about floor plans.

This is why two parcels that look identical in the assessor's file, same acreage, same zoning district, can support very different homes once you get past the cover page. A flatter lot down the road might clear the buyer for a substantially larger residence than a hillside lot at the same price point. Slope isn't a footnote in this town. It's a line item in the math.

A Better Number Than Price Per Square Foot

This is where the standard cross-town comparison breaks down. As of the three months ending May 2026, the median sale price in Los Altos Hills sat at $5.3 million, with a median price per square foot around $1.66 thousand. In the same window, neighboring Los Altos, sharing zip codes and a border but not the zoning code, posted a lower median sale price at $4.2 million, yet a higher median price per square foot at roughly $1.94 thousand.

Read quickly, that looks like a contradiction. The town with the higher median price is somehow cheaper per square foot than the one next door. It isn't a contradiction once you separate what each price is actually paying for. Los Altos Hills' price reflects the acre and everything that comes with holding it, privacy, setback, the buildable envelope math. Los Altos, built out on a quarter-acre minimum since its own 1952 incorporation, is pricing built square footage more directly, because there's proportionally less unbuilt land absorbing the premium.

Run the math on Los Altos Hills' own development area formula and the gap gets sharper. Apply the reported median sale price, $5.3 million for the three months ending in May 2026, across the two ends of the slope tier as an illustration: divide it by 15,000 square feet of allowable development area and the implied cost lands around $353 per permitted square foot. Divide the same figure by the 7,500 square-foot floor and it climbs to roughly $707. Same purchase price, same acre, twice the effective cost of what you're actually allowed to build, depending entirely on where that parcel falls on the slope table.

The lesson isn't that one town is a better value than the other. It's that price per square foot, the number every portal leads with, measures something different in each market. In Los Altos, it's a reasonably direct read on built space. In Los Altos Hills, it's blended with land you may or may not be able to build on.

What Else the Acre Comes With: Pathways and Septic

The Greenhills Court decision wasn't an isolated case. The same Pathways Committee spent 2026 working through a pending pathway on Magdalena Avenue, estimated at $350,000 to $400,000 with construction potentially starting that summer, a separate project on Summerhill Avenue held up on a county encroachment permit, and an open question over whether to remove or limit the Chaparral pathway easement after a sign dispute with an affected family. None of this is unusual. It's the routine business of a town whose pathway network runs more than 80 miles, largely built from easements dedicated during original subdivision, that residents and visitors use for walking, running, and riding.

For a buyer, the practical takeaway is that these easements can dictate where a pool, tennis court, or accessory dwelling unit is allowed to go, regardless of what the raw lot dimensions suggest. Before finalizing plans for a property, it's worth pulling the town's pathway map for that specific parcel rather than assuming the buildable area is whatever isn't already occupied by the house.

Septic carries a similar catch. Town code requires connection to the public sewer system, rather than continued reliance on a septic system, whenever a public sewer main sits within 200 feet of the parcel. On a property advertised with a septic system, that distance is worth confirming early, since it can affect both renovation cost and timeline.

Why the Neighboring Zip Code Confusion Costs Buyers Real Money

The quarter-acre versus one-acre split between Los Altos and Los Altos Hills isn't incidental. It's the reason the town exists as a separate municipality. When Los Altos incorporated in 1952 at a quarter-acre minimum, the hillside residents who would become Los Altos Hills organized to protect their acre lots and the right to keep horses on private property, distributing their case to neighbors on green paper in the fall of 1955 before incorporating in January 1956. That founding decision is still the zoning code today.

Because the two towns share zip codes and sit against each other on a map, it's easy for a buyer relocating from outside the region to treat them as variations on one market. The zoning history says otherwise, and so does the price-per-square-foot data. Comparing a listing in each town on that single number, without accounting for what the acre is doing to the math, is the fastest way to misjudge what you're actually being asked to pay for.

Before You Write an Offer

A few steps make the acre-versus-square-footage gap concrete before you're committed:

1. Request the parcel's slope-density worksheet, not just the lot size on the listing sheet. The town's Maximum Development Area and Maximum Floor Area figures are calculable for any specific parcel and tell you what's actually buildable.
2. Pull the pathway map for the property. If an easement crosses it, confirm whether it affects where a pool, ADU, or major addition could go.
3. Check the distance to the nearest public sewer main. Within 200 feet, a septic system may not be an option going forward.
4. Budget for permitting time realistically. The town's own published average from site development permit submittal to building permit issuance runs 13 to 17 weeks, and complex hillside sites often take longer.

A Few Questions Worth Asking Early

Does a bigger lot always mean a bigger allowable house in Los Altos Hills? No. Once slope enters the town's development area formula, two one-acre lots can support very different maximum square footage.

If a pathway easement crosses my lot, can I have it moved? Sometimes, but not automatically. The town's Pathways Committee weighs safety and access for existing users before approving a change, and has declined relocation requests when the current alignment serves that purpose better.

How soon after closing could I break ground on a remodel or new build? Plan for roughly 13 to 17 weeks between submitting a site development permit and receiving a building permit, based on the town's published average, with more complex slope or easement situations running longer.

Reading a Los Altos Hills listing well means reading past the acreage line. The slope table, the pathway map, and the sewer distance all shape what that acre is actually worth to you, and none of them show up in a median price. If you're weighing a hillside parcel against something in Los Altos or Palo Alto and want the buildable numbers run before you make an offer, Bob Kamangar has spent close to four decades on the construction and permitting side of this exact question, and can walk the site-specific math with you before you're standing at the closing table.