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HomePropertyValues
Methodology

Sources and workings

Data sources

  • House price index. Federal Housing Finance Agency, All-Transactions House Price Index, covering 51 states and 410 metropolitan areas, quarterly, currently to 2026Q1. Source. This is a repeat-sales index, so an index value is not a dollar price and is never presented as one.
  • Mortgage rates. Freddie Mac Primary Mortgage Market Survey, 30-year and 15-year fixed, via the Federal Reserve Bank of St. Louis. Weekly, fetched live.
  • Median sale price. US Census Bureau and Department of Housing and Urban Development, median sales price of houses sold, via FRED. Quarterly, fetched live.
  • Property tax rates. Census Bureau American Community Survey, median real estate taxes paid as a share of median home value, statewide, 5-year estimates.

The adjustments, stated exactly

Nothing here is hidden behind a model. These are the numbers applied:

  • Condition. Needs work ×0.82, below average ×0.93, typical ×1.00, standout ×1.09. Applied against a local average property.
  • Age. Built before 1960, ×0.96, reflecting systems risk in unrenovated older stock.
  • Benchmark baseline. National median sale price divided by a 2,200 square foot typical home, then scaled by the ratio of your area's index to the median US state index.
  • Rent bracket. Value divided by a price-to-rent ratio of 14 to 20 times annual rent, which spans most US markets. Wide on purpose.
  • Borrowing capacity. 80% of estimated value less the outstanding balance, the conventional combined loan-to-value ceiling.

How the range is set

For the indexed method the band starts at ±5% and widens by 0.8 points for each year you have owned the property, capped at ±18%. The reasoning is that the index measures an area rather than a specific house, and the gap between one house and its local average grows with time.

For the benchmark method the band is a flat ±24%, which is wide because the method is weak. If that range is too wide to be useful, that is the honest signal: find your purchase price and use the other method.

Confidence

The confidence figure reflects the method used and how complete your inputs were. It is not a probability and it is not calibrated against actual sale outcomes, because we do not observe actual sale outcomes. It is a legibility score for the estimate, and the page says so where it appears.

Known limitations

  • No parcel, deed, or assessor data, so no address-level lookup.
  • No comparable sales, which is the strongest input a real valuation uses.
  • Condition is self-reported and unverified.
  • Statewide property tax rates conceal very large county-level variation.
  • Index data lags by roughly one quarter.
  • The FHFA index covers conforming, conventional mortgages, so it under-represents cash sales and the very top of the market.

Corrections

If you find an error in a figure, a rate, or a calculation, write to hello@homepropertyvalues.com. See also how the estimate works.