About RentIndex
What should rent actually cost?
What we do
RentIndex compares local rents to HUD Fair Market Rent and area income so renters know when a listing is fair.
We focus on U.S. rent, Fair Market Rent, and housing affordability. Every page on rentindex.org is built from HUD Fair Market Rent data and the Census ACS, cited and linkable so readers can trace any number back to its source.
Who runs this
RentIndex is built and maintained by the RentIndex Team. We're a small group working on making public U.S. rent, Fair Market Rent, and housing affordability data easier for non-specialists to read. If you have a correction, a data tip, or a question about how a number was derived, the contact email below reaches us directly.
Who this is for
RentIndex is built for renters, landlords, housing reporters, and affordability researchers.
Why this exists
Public data on U.S. rent, Fair Market Rent, and housing affordability is technically free, but practically locked behind file formats, acronyms, and paywalled dashboards. RentIndexexists to close that gap: take the raw federal and public-sector data, and turn it into pages a normal person can read in thirty seconds.
How we work
- Primary source only. We pull from HUD Fair Market Rent data and the Census ACS and cite the exact dataset and version on every page.
- No invented numbers. If a figure is not in the underlying public data, it does not appear on rentindex.org. We never generate synthetic statistics to fill gaps.
- Methodology, in plain English. We combine HUD Fair Market Rent by bedroom count and metro with Census ACS contract and gross rent distributions to produce a fair-rent-vs-actual comparison per ZIP and metro. Affordability pages use 30-percent-of-income thresholds against local median household income.
- Refreshed on a schedule. Refreshed annually — HUD publishes a new FMR effective October 1 each year.
- Corrections welcome. Readers flag issues all the time. When the source fixes a record, RentIndex follows.
Known limitations
FMR is a HUD policy number used for Section 8 voucher caps, not a market-clearing price — in hot markets, asking rents can be 20-40 percent above FMR. ACS rent data is a 5-year rolling average and lags listing-site data by at least a year.
Why HUD Fair Market Rents are the right base layer for rental data
The U.S. Department of Housing and Urban Development publishes Fair Market Rents (FMRs) annually for every U.S. metro and non-metro county. The FMR system was originally built to set Section 8 voucher payment standards — HUD needs an objective number for what a modest unit costs in each market, and the methodology has been refined for decades to produce that number defensibly.
For public rental-market analysis, the FMR dataset is the cleanest available baseline. It covers the entire country at the county level, uses a consistent methodology across markets, and is republished annually with a transparent calculation. It does not replace local listings data for a specific apartment hunt, but it provides the structural picture of what rent looks like at scale across the country in a way that listings data — fragmented, paid, and methodologically inconsistent — cannot.
RentIndex builds the public-facing presentation around HUD FMR with secondary inputs from Census ACS housing tables and Bureau of Labor Statistics CPI for shelter inflation. Every numeric value on the site links back to the originating federal dataset.
How the data pipeline is structured
The pipeline pulls HUD Fair Market Rents annually when HUD publishes the new fiscal-year vintage (typically September). The pull touches every county and every bedroom size (0BR, 1BR, 2BR, 3BR, 4BR). Census ACS housing data — median rent, median household income, rent-to-income ratio — pulls on the same cadence as Census’s ACS 5-year release. CPI shelter inflation pulls monthly from the BLS API.
The per-county and per-state pages combine these inputs into a single profile. Median rent comes from ACS; the affordability ratio comes from ACS rent against ACS income; the affordability trend uses CPI shelter inflation as the rate-of-change input. The methodology page describes every input series with the federal source URL.
Refresh cadence varies by data product: HUD FMR is annual, Census ACS is annual on a 5-year-rolling basis, BLS CPI is monthly. The site stamps the as-of date for every value so readers know which underlying release a given number reflects.
Where rental data has known limitations
Three things to keep in mind. First, HUD Fair Market Rents are an estimate of the 40th-percentile asking rent for modest-quality units in each market — they are not a survey of all listings, and they exclude high-end new construction. In rapidly-changing markets, FMRs can lag actual asking rents by a year or more.
Second, Census ACS rent data covers occupied units rather than asking rents on currently-empty units. The ’rent paid’ distribution in ACS therefore includes long-tenured renters paying below-market rent and recent movers paying market — the median is real but does not equal what a new renter would pay in the market today.
Third, neither HUD FMR nor Census ACS captures the subsidized-vs-market-rate split cleanly. Counties with substantial public housing or Section 8 voucher use will have lower ACS median rents than the unsubsidized market rate, because the subsidized units pull the distribution down. The per-county pages show both the HUD FMR and the ACS median for that reason.
Independence
RentIndex is an independent publication. We are not funded, owned, or directed by any of the agencies, companies, or organizations that appear in our data. Hosting is paid for by advertising — see our Privacy Policy for details — and we do not take paid placements, sponsored rankings, or "remove-my-entry" fees.
History
RentIndex launched in 2026 as part of a small portfolio of independent public-data sites. It has been maintained and updated continuously since.
Contact
Tips, corrections, data-partnership questions, and press inquiries: hello@rentindex.org. More options on our contact page.