San Diego County Home Equity Since You Bought

Updated October 2026 · Rudy Flores

If you bought a new home, the number to start with is your final contract price, including upgrades and any lot premium. This estimator applies the month-by-month change in Zillow's typical values for your area to that figure.

You will also see the principal paid so far, your estimated equity and a likely net if you sold. Builder pricing and resale prices can differ, so Rudy can check the estimate against recent resales near you.

This is an estimate for planning, from Zillow's ZIP-wide typical values applied to your purchase price. It is not an appraisal, a broker price opinion, an offer, a loan offer, or tax or legal advice, and Rudy is a real estate agent, not a lender, appraiser or tax professional.

How the estimate works

1. The page takes Zillow's index for your area and home type in the month you closed with the builder, and again in the newest month.
2. Your contract price moves by that change, and the condition setting forms the range.
3. With the purchase loan still in place, the balance is estimated from normal fixed-rate payments beginning the month after closing.
4. Equity is the midpoint minus that balance; the net subtracts selling costs too, and is before taxes.
5. The Prop 13 figure starts at your contract price and grows by the Board of Equalization's factor for each tax year, at most 2%.

Your Prop 13 value and Prop 19

A new home's taxable value starts at its purchase price, and Prop 13 then limits yearly increases to 2%. Special taxes in newer communities, such as Mello-Roos, are billed separately and are not part of this estimate.

Later on, if you are 55 or older and moving to another California home, Proposition 19 may let you transfer the taxable value, as long as the new purchase falls within two years of your sale; it is available three times. The county assessor decides.

Planning a later move? Bookmark the downsizing calculator.

Sources and dates

• Zillow Research, Zillow Home Value Index (ZHVI) by ZIP code: all homes, single-family and condo; middle tier, smoothed and seasonally adjusted (data through September 2026, files updated Oct 16, 2026)
• FHFA House Price Index for five-digit ZIP codes (annual, developmental index, not seasonally adjusted; 2000 = 100), used only for purchases before Zillow's series begin. Citation: Bogin, Doerner and Larson, Local House Price Dynamics: New Indices and Stylized Facts, FHFA Working Paper 16-01 (annual, through 2025)
• Freddie Mac Primary Mortgage Market Survey (PMMS): weekly 30-year and 15-year fixed averages; the page uses the mean for your purchase month (monthly means through October 2026; latest weekly 30-year average 7.24% on Oct 29, 2026)
• California State Board of Equalization, Letter To Assessors No. 2026/002: inflation factors for 1976-77 through 2026-27, with Revenue and Taxation Code section 51 and California Constitution article XIII A, section 2(b) (January 13, 2026)
• California State Board of Equalization, Proposition 19 (checked Oct 30, 2026)
• Assumptions, not sourced figures: the condition range (the same rule of thumb as the home value range tool), 6% selling costs, 20% down, regular payments on a fixed-rate loan starting the month after you bought, and the first inflation factor applying on the first January 1 after your purchase

Questions owners ask

More from Rudy

• Take the Home Strategy Quiz
• Request a Home Value
• Compare My Selling Options
• What Could My Home Sell For?
• Seller Net Proceeds Estimator
• Downsizing Calculator
• Keep or Sell Calculator
• Home Sale Tax Exclusion Estimator
• Buy First or Sell First Planner
• Book a 15-minute call