Housing Inventory Explained: What Active Listings and Months of Supply Actually Measure

"Housing inventory" sounds like a single number. It is not. Active listings, new listings, pending listings, existing-home inventory, and months of supply all describe different parts of the for-sale housing market, and they answer different questions. Realtor.com counted 1,161,615 active listings in September 2026, while NAR reported 1.60 million units of existing-home inventory for the same month — and neither figure is wrong. They measure different things.

This article explains what active listings and new listings actually measure, how pending listings fit in, why Realtor.com and NAR report different inventory figures without contradiction, and what months of supply does — and does not — tell you about a market.

About the data

This article draws on two related but distinct data products: Realtor.com's Monthly Housing Trends report and the National Association of Realtors' (NAR) Existing-Home Sales release, both for September 2026. Each has its own methodology, sample, and listing universe. None of the figures below are blended into a single trend line.

What "housing inventory" actually means

"Housing inventory" is not one universal, standardized number. Different metrics answer different questions about the for-sale market.

Active listings measure current active for-sale stock. New listings measure the flow of homes entering the market during a period. Pending listings measure under-contract stock. Contract signings, or newly pending listings, measure the flow into pending status. NAR's existing-home inventory is a source-specific measure of existing-home inventory. Months of supply measures inventory relative to sales pace. These are related concepts, but they are not the same measure, and they should not be collapsed into one number.

What active listings measure

Realtor.com's active listing count is a stock, or snapshot, measure. It represents approximately the count of active listings expected on a given day of the specified month. It tracks active for-sale listings and excludes pending listings where pending status is available.

The September 2026 Realtor.com listings universe includes existing single-family homes, condos, townhomes, row homes, and co-ops. New construction is generally excluded unless it is supplied via an MLS that contributes listing data to Realtor.com.

The 1,161,615 active listings figure for September 2026 should not be read as homes newly listed during September, all homes in the United States, total U.S. housing stock, or NAR's existing-home inventory figure. It is specifically the active for-sale stock, within Realtor.com's listing universe, on a typical day in the month.

In September 2026, active listings rose 1.9% from August and were up 5.4% from a year earlier, but remained 5.2% below September 2019.

New listings are a flow, not an inventory stock

New listings describe homes entering the market during the period — a flow, not a stock. A newly listed home can enter active inventory, but active listings and new listings should not be added together, because active listings already reflect a snapshot that includes homes listed in prior periods, not only homes newly listed in the current period.

In September 2026, new listings totaled 394,830, down 1.7% from August and down 0.7% from a year earlier, and 12.9% below September 2019.

Where pending listings fit

Pending listings are a separate stock: homes currently under contract. The pending listing count is not the same as newly pending listings or contract signings, which describe the flow of homes entering pending status during a period.

Total listing count combines active listings and pending listings — active listings plus pending listings, not active listings plus new listings. Pending stock and contract-signing flow should not be mixed with each other, any more than active-listing stock should be mixed with new-listing flow.

Why Realtor.com and NAR report different inventory numbers

Realtor.com's active listings figure and NAR's existing-home inventory figure are not interchangeable.

NAR's monthly Existing-Home Sales indicator is based on a representative sample of 210 Boards/MLSs, with aggregated raw volume figures weighted to represent activity for each census region. Realtor.com's active listings figure draws on a different listing universe and a different methodology, built around the count of active listings expected on a given day of the month.

Different definitions, different datasets, different coverage, and different methodologies can produce different inventory figures without either one being wrong. This article does not calculate a raw difference or a percentage difference between Realtor.com's 1,161,615 active listings and NAR's 1.60 million units of existing-home inventory, and does not label either figure as more accurate or more correct. They are simply not measuring the same thing.

What the latest national inventory data shows

Each row in this table belongs to its own source and its own metric. Realtor.com's active-listings and new-listings figures should not be read as though they share a methodology with NAR's existing-home inventory and months-of-supply figures, even though all four describe September 2026.

What months of supply actually measures

Months of supply is the number of months it would take for current inventory to sell given the current sales pace.

Months of supply is a pace, or ratio, measure — inventory relative to the current sales pace — not a raw inventory count and not a forecast. It should not be read as "the existing inventory will sell in 4.8 months." The correct interpretation is that 4.8 months expresses current inventory relative to the current sales pace, if that relationship were held constant, which it generally is not.

In September 2026, NAR reported existing-home sales at a 3.99 million seasonally adjusted annual rate (SAAR), up 1.5% from August but down 2.2% from a year earlier. A SAAR figure describes an annualized pace, not a literal count of September transactions.

Why months of supply can change even when listing counts do not

Months of supply can move even when the underlying listing count does not, because it depends on both inventory and sales pace.

These are conceptual relationships, not forecasts, and not specific observed values from any single period. This article does not state or imply a universal threshold — it does not claim that six months of supply defines a "balanced" market, that below six months defines a "seller's market," or that above six months defines a "buyer's market." No such universal rule is implied by the months-of-supply measure itself.

More inventory does not automatically mean a buyer's market

Rising active listings, rising new listings, or rising months of supply do not, on their own, establish that negotiating conditions have shifted toward buyers in a given market. Months of supply is a national, source-specific pace measure; local conditions, price points, financing conditions, and buyer and seller behavior all vary by market and are not captured by a single national inventory or months-of-supply figure.

Housing inventory is not the same as total housing supply

For-sale inventory is not the same as total housing stock. Listing an existing home changes its market status, not the number of housing units that exist. Changes in the total housing stock are measured separately from listing activity; new residential construction is one major source of additions.

Housing inventory, housing starts, and rental vacancy answer different questions

For-sale inventory, housing starts, and rental vacancy describe different parts of the housing market and answer different questions.

Housing starts describe the beginning of new privately owned residential construction — read more about how permits, housing starts, and completions measure the construction pipeline. This article describes for-sale availability and inventory measures specifically, not the construction pipeline.

Rental vacancy concerns vacant rental inventory, not homes offered for sale — read more about what the rental vacancy rate can and cannot tell you about housing supply. Active listings concern homes offered for sale, a different part of the housing market from rental vacancy.

What housing inventory can—and cannot—tell you about a market

Housing inventory data can tell you:

• how much for-sale inventory is available
• whether inventory is rising or falling
• how inventory compares with sales pace
• the difference between stock and flow within a given source
• comparable trends over time, when methodology is held consistent

On its own, housing inventory data cannot tell you:

• whether housing is affordable — see median household income by metro area for income context
• whether there is a structural housing shortage
• whether prices will fall
• whether demand will rise
• whether rents will change
• total housing stock
• rental availability
• future sales
• investment performance
• universal buyer or seller negotiating power

How to compare housing inventory across markets

Comparing housing inventory across markets requires holding the source and methodology constant. A Realtor.com active-listings figure for one market should be compared with a Realtor.com active-listings figure for another market, not with a different source's inventory measure. The same applies to months of supply: compare NAR's months-of-supply figure across markets or over time using NAR's own data, not a blend of sources.

You can explore Metro Analytics market pages for local context, and the Metro Analytics methodology explains how these measures are defined and sourced.

The takeaway

Housing inventory is not one universal, standardized number. Active listings, new listings, pending listings, existing-home inventory, and months of supply each answer a different question, and Realtor.com and NAR figures are not interchangeable with each other.

Strong interpretation requires:

• distinguishing stock measures from flow measures
• keeping Realtor.com and NAR figures separate rather than combining or comparing them directly
• reading months of supply as a pace/ratio measure, not a forecast
• avoiding any universal buyer's-market or seller's-market threshold
• distinguishing for-sale inventory from total housing stock, housing starts, and rental vacancy
• pairing inventory data with affordability, supply, and demand indicators for a fuller picture

If you want to look at inventory conditions alongside other signals for a specific area, you can start with Metro Analytics Markets, or review the Methodology to see how these measures are used.