Foster City Neighborhoods by Their Lots: Single-Family Lot Sizes and Flood Zones

Foster City’s public parcel records give the zoning and an outline for every parcel in the city. We took the 4,542 lots zoned single-family (R-1, including R-1 planned developments), 1,500 square feet or more, measured each from its outline, placed it in our neighborhood guide outlines, checked its center against FEMA’s flood map and checked each lot against CAL FIRE’s fire hazard severity zone maps. This post is about the land: lot sizes, flood zones and fire zones. Foster City’s many townhomes, condos and apartments aren’t counted, so it covers the single-family lots only. The figures come from City of Foster City parcel and zoning records, October 2026. There are no addresses or owner details here.

The short answer

• The median lot zoned R-1 or R-1/PD is 5,810 sq ft, and every neighborhood’s median falls between 5,710 sq ft and 6,150 sq ft.
• Largest median lot: Treasure Isle (6,150 sq ft). Smallest: Marina Point & Harbor Side (5,710 sq ft).
• Most single-family lots: Sea Colony & Port Royal, with 1,434 of the city’s 4,542.
• Flood zones: one of the 4,542 lots has its parcel center in a FEMA high-risk zone (AE), in Treasure Isle.
• Fire zones: no single-family lot touches a CAL FIRE fire hazard severity zone.

Neighborhood by neighborhood

Largest median lot first. “Single-family lots” counts lots zoned R-1 or R-1/PD inside each guide’s outline; every one of the city’s 4,542 falls inside exactly one guide. Each name opens its guide. The Islands has no single-family lots (its homes are townhouse and condominium groups), so it’s left out of the table.

What stands out

• The lots are remarkably even. The largest and smallest neighborhood medians are only 440 sq ft apart, so lot size rarely separates one Foster City neighborhood from another.
• Sea Colony & Port Royal holds about a third of the single-family lots: 1,434 of 4,542 (32%).
• Flood and fire zones barely touch these lots: one lot in zone AE and none in a fire zone.

Reading it right

• Zoning isn’t use. We counted lots zoned R-1 or R-1/PD, 1,500 square feet or more; a few may hold a second unit, and townhomes, condos and apartments aren’t counted.
• Lot sizes are measured from the city’s parcel outlines, so they can differ from a survey by a few percent.
• We checked the center of each lot against FEMA’s National Flood Hazard Layer. Maps change, so check the current FEMA map for the exact address.
• Zone X isn’t zero risk. Flooding can happen outside the high-risk zones, and flood insurance is optional there.
• A median isn’t a verdict. It describes the lots, not which neighborhood is right for you.

Go deeper

Foster City Housing Market by the Numbers covers prices and bidding, and Foster City Neighborhoods Ranked by Price per Square Foot compares the neighborhoods on price. Flood & Fire Zones by Neighborhood compares every guide we write, and the Foster City guide page links every neighborhood guide.

The Foster City data series: housing market by the numbers · neighborhoods ranked by price per sq ft · where homes sell over asking · ten years of prices by neighborhood · condos and townhomes · house prices by bedrooms · houses under $2M · houses at $2.8M and up · the best month to sell

Planning a rebuild or an addition?

A Property Nerd can pull the zoning, the lot and the recent sales on your street before you plan. Call (408) 373-1660 or (650) 383-8606, or book a strategy call. Commissions are negotiable, and we offer bundled services, so ask us what’s included.