Months of Supply: How to Tell a Buyer's Market From a Seller's Market

The short answer: Months of supply estimates how long the homes currently for sale would last at the recent pace of sales if no new listings came on the market. A low number means homes are being absorbed quickly, which tilts toward sellers. A high number means more choice and more time for buyers. NJ REALTORS® calculates it as the inventory of homes for sale at the end of a month divided by the average monthly pending sales over the last 12 months (NJ REALTORS® Monthly Indicators, September 2026).

For where to find NJ market reports in the first place, see our guide to reliable NJ housing market data. This page is about reading one of the most quoted numbers in them.

How is months of supply calculated?

The idea is always inventory divided by the pace of sales. The details differ by source:

Sources: NJ REALTORS® Monthly Indicators; Census/HUD New Residential Sales.

Those differences matter. A figure built on pending sales reacts to new contracts sooner than one built on closings. A 12-month average smooths out seasonal swings. A new-construction figure tells you about builders' inventory, not the resale market most buyers shop in.

What does months of supply look like in NJ right now?

As an example of how to read it, NJ REALTORS®' report for September 2026 showed statewide months of supply for all properties at 3.3, up from 2.9 a year earlier. By property type it showed:

• Single family: 3.1 (from 2.9)
• Townhouse-condo: 3.9 (from 3.0)
• Adult communities: 3.4 (from 2.9)

The report says its data came from the state's multiple listing services as of October 9, 2026, with a margin of error of plus or minus 4% for statewide numbers (NJ REALTORS®). These numbers change every month, so always quote the report date with the figure.

Is there an official number for a balanced market?

No. You'll often hear that about six months of supply means a balanced market. That's an industry rule of thumb, not an official standard, and none of the government or NJ REALTORS® sources cited here sets a threshold.

A more useful way to read the number:

• Direction: Is supply rising or falling compared with a year ago? Comparing the same month each year avoids seasonal noise.
• Segment: Is one property type or price range moving differently? In the September 2026 report, townhouse-condo supply rose faster than single-family supply.
• Confirmation: Do other measures agree? The same reports show days on market and the percent of list price received (NJ REALTORS®). Rising supply with longer days on market and lower list-price ratios points the same way. Mixed signals call for caution.

Why can two reports disagree?

Here's an example with made-up numbers, for illustration only. Suppose a town has 60 homes for sale at the end of June:

Same inventory, different answers. Whenever one month's sales run above the yearly average, a single-month figure looks tighter than the 12-month version. When you compare towns or quote a number to a client, use the same source and method each time.

Small areas are also noisy. In a town with a handful of sales a month, a few listings coming or going can swing the figure a lot. Be careful reading too much into a single small-market month.

How do agents use months of supply with clients?

Our suggestions:

• With sellers: Pair the number with your pricing work. A comparative market analysis shows what similar homes sold for, and months of supply shows how much competition a new listing will face. Both belong in a listing presentation.
• With buyers: Use it to set expectations about how quickly to decide and how much room there may be to negotiate, without promising either.
• With everyone: Explain what it doesn't capture. Mortgage rates shift demand quickly (how rates affect NJ buyers), and a statewide figure can hide very different local conditions.
• Attribute it. Name the source and the month, and don't present a forecast as a fact.

Municipality-level reports from NJ REALTORS® require a member login, and the association says only REALTORS® can provide them to buyers and sellers (NJ REALTORS®). Our MLS guide explains how agents get access to listing data.

Valuation and market analysis is a section of the PSI licensing exam outline (PSI candidate bulletin), and reading reports like these builds on it. Business Elementary's 75-hour course covers it from the ground up.

Sources

• NJ REALTORS®, Monthly Indicators, New Jersey, September 2026 (data as of Oct. 9, 2026; prepared by ShowingTime Plus): https://njar-public.stats.10kresearch.com/docs/mmi/2026-09/x/report?src=page
• U.S. Census Bureau and HUD, Monthly New Residential Sales, September 2026 (released Oct. 27, 2026): https://www.census.gov/construction/nrs/pdf/newressales.pdf
• NJ REALTORS®, Housing market data (10K): https://www.njrealtor.com/research/10k/
• PSI, New Jersey Real Estate Candidate Information Bulletin (updated 2/1/2026): https://test-takers.psiexams.com/api/content/bulletin/1667

Last reviewed: November 1, 2026

Frequently Asked Questions

Is months of supply the same as months of inventory?

Yes, the terms are used interchangeably. What matters is the formula behind the number, so check the report's definition.

Does low months of supply mean prices will rise?

Not necessarily. It describes current competition among listings, not a forecast. Prices also depend on rates, incomes and buyer demand.

Why does NJ REALTORS® use pending sales instead of closed sales?

Its report defines the measure using the average monthly pending sales over the last 12 months (NJ REALTORS®). Pending sales reflect new contracts, which show up before closings do.

Can I calculate months of supply for a single neighborhood?

You can, with MLS data, but small numbers swing widely. Use several months or a 12-month average, and say clearly how you calculated it.