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
- We check the Zillow index for your home type and ZIP code at your purchase month and at the latest month; before 2000, FHFA's yearly ZIP index fills in.
- That change is applied to what you paid, and the condition you choose sets the range.
- If you still carry the purchase loan, its balance follows the regular fixed-rate payments from the month after you bought.
- Equity is the midpoint less any loan; deduct selling costs as well and you get a net before tax.
- Your Prop 13 estimate compounds the price you paid by the Board of Equalization's yearly factors, each one 2% or less.
Your Prop 13 value and Prop 19
For long-time owners, the Prop 13 gap is often the surprise. Your taxable value started with what you paid and has been allowed to grow only 2% or less per year, so after many years it can sit well below market value.
At 55 or older, Proposition 19 may let you keep that lower taxable value when you move, wherever in California your next home is, if you buy it within two years of selling. It works up to three times; confirm eligibility with the county assessor.
If staying for good turns into a smaller home, start with 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
I bought before 2000. Does this still work?
Usually. Zillow's ZIP data starts in 2000, so earlier purchases use FHFA's yearly ZIP index to reach Zillow's first full year. A few ZIP codes lack the older index, and the page says so.
How far off could this be?
A ZIP-wide index cannot see decades of upkeep, additions or a remodel, so a long-held home can land outside the range. Rudy reviews recent nearby sales for free for a real value.
My home is paid off. What do I pick?
Choose "No loan (paid off or paid cash)." If you have a reverse mortgage or an equity line, pick the second option and enter that balance instead.
Is my Prop 13 value my home's value?
No. It is the base your property tax uses, which started at your purchase price and rises 2% or less a year; after a long time it is often far below market value. Your tax bill shows the exact figure.
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