Data credibility policy
Housing data sources, definitions, and update dates
Every indexed city page identifies where its starting values came from, what they measure, when they were observed, and which inputs are only modeling assumptions. The current batch was reviewed September 16, 2026.
Observed inputs are not forecasts
Sourced observations
- Zillow typical home value and typical observed rent
- Recent Zillow index changes calculated from monthly values
- U.S. Census median real-estate tax and home-value estimates
- Freddie Mac national 30-year fixed mortgage-rate average
Modeling assumptions
- Future home appreciation and rent growth
- Investment return, maintenance, and insurance
- Purchase and sale costs, HOA, and mortgage insurance
- Down payment, loan term, and how long the user stays
The calculator never treats a recent price change as a forecast. Its future-looking assumptions are shown alongside the result and are applied consistently to both scenarios.
Primary data sources
Zillow housing indexes
City starting values use the all-homes, middle-tier, smoothed and seasonally adjusted Zillow Home Value Index (ZHVI), plus the all-homes Zillow Observed Rent Index (ZORI). The observations on this site currently run through August 31, 2026. ZHVI is a typical home value—not a median sale price. ZORI is a repeat-rent measure of asking rents—not the average rent paid by all tenants. Source: Zillow Research, Zillow Home Value Index (ZHVI) and Zillow Observed Rent Index (ZORI). Data accessed September 16, 2026.
U.S. Census property-tax input
The city-level property-tax planning rate divides median annual real-estate taxes from 2024 ACS 5-year table B25103 by median owner-occupied home value from table B25077. The 2024 release pools survey data collected from 2020 through 2024. This ratio is useful as a broad starting point, but it is not a statutory millage rate or a parcel-level effective tax rate. ACS home value is respondent-estimated market value rather than taxable assessed value, and reported taxes can reflect exemptions. The calculation also combines two separately estimated medians, each with a published 90% margin of error.
Freddie Mac mortgage rate
The default mortgage input is 6.76%—Freddie Mac's U.S. average for a 30-year fixed-rate mortgage as of September 10, 2026. It is a national survey average, not an advertised offer, APR, borrower quote, or city-specific rate.
Current source-reviewed city inputs
| City | Typical home value | Typical monthly rent | Property-tax input | Reviewed |
|---|---|---|---|---|
| Knoxville, TN | $370,699 | $1,712 | 0.64% | September 16, 2026 |
| Nashville, TN | $429,741 | $1,834 | 0.60% | September 16, 2026 |
| Oakland, CA | $708,610 | $2,735 | 0.92% | September 16, 2026 |
| Oklahoma City, OK | $207,421 | $1,282 | 1.00% | September 16, 2026 |
| Lubbock, TX | $212,039 | $1,333 | 1.57% | September 16, 2026 |
| Santa Fe, NM | $581,279 | $1,925 | 0.48% | September 16, 2026 |
| Des Moines, IA | $210,572 | $1,126 | 1.80% | September 16, 2026 |
| Memphis, TN | $145,335 | $1,232 | 1.09% | September 16, 2026 |
| Madison, WI | $426,336 | $1,616 | 1.75% | September 16, 2026 |
Calculation and update rules
- One-year index changes compare the latest monthly value with the same month one year earlier: latest ÷ prior year − 1.
- Price-to-rent equals the latest typical home value divided by 12 times the latest typical monthly rent. It is descriptive, not a buy-or-rent decision rule.
- Source values are rounded for display. Calculator inputs use the displayed whole-dollar housing values and displayed tax rate.
- We target a monthly review of Zillow city inputs and a review of the mortgage-rate starting point whenever a data batch is updated. The visible observation and review dates—not the current calendar date—tell you how fresh a page is.
- Source publishers may revise historical series. A page is not silently presented as live; its recorded review date remains until the source check is repeated.
How to use these numbers
City indexes are useful orientation, not a substitute for a comparable listing, lease quote, lender offer, insurance quote, or property-tax record. Start with a sourced city page, then replace the visible home price and rent with figures for the same type of home.
Browse sourced city calculators