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EXPLAINER

What Is the Case-Shiller Index?

By · Editorial standards · Updated June 25, 2026

Direct answer

The Case-Shiller Home Price Index is the most widely cited measure of US home price changes over time. It tracks repeat sales of the same properties, which filters out the noise of housing mix and quality changes. The national index (CSUSHPINSA) is the version most commonly referenced in financial media and research.

How it works

Case-Shiller uses a repeat-sales methodology. Instead of tracking the average price of all homes sold in a given month (which shifts when different types of homes sell), it tracks the price change of the same home sold at two different points in time. This isolates true price appreciation from changes in what's being sold.

The index was developed by economists Karl Case and Robert Shiller in the late 1980s. It is published by S&P Dow Jones Indices (now S&P CoreLogic) with data from CoreLogic.

The national index, CSUSHPINSA, covers all nine US Census divisions and is the broadest measure of single-family home price change in the United States.

How Aspire uses Case-Shiller

Aspire references Case-Shiller (CSUSHPINSA) as a national housing benchmark on the methodology page. For city-level future-cost pages, Aspire uses Zillow ZHVI because it provides metro-level granularity. Both indices measure home price growth; they differ in coverage and methodology.

The trailing 10-year compound annual growth rate (CAGR) from these indices is what Aspire uses to model the future cost of a home. That rate is not a prediction — it is the historical cost-growth rate of the goal, at these assumptions.

Case-Shiller vs Zillow ZHVI vs FHFA HPI

Index Methodology Coverage Granularity Aspire Use
Case-Shiller (CSUSHPINSA) Repeat sales National (9 Census divisions) National only National housing benchmark
Zillow ZHVI Zestimate-based smoothed index National + metro + ZIP Metro-level City future-cost pages
FHFA HPI Repeat sales (Fannie/Freddie mortgages) National + metro + state Metro-level Not currently used

All three are reputable. The key difference for future affordability is that Zillow ZHVI provides the metro-level data Aspire needs to answer "what will a home in your city cost" — not just the national average.

Why this matters for future affordability

CPI includes a housing component (rent of primary residence and owners' equivalent rent), but it does not track the purchase price of homes. If you are trying to buy a home, the relevant cost-growth rate is the home price index for your city, not CPI.

That distinction is the core of future affordability: the life you want has its own inflation rate, and for most people, housing is the largest line item in that rate. See your number →

Sources

See methodology →