Fair Market Rent (HUD) isn't the Market Rate, and in Phoenix it's 29% Higher

In Phoenix the HUD-based two-bedroom figure in our data runs about $2,023 a month while actual market rent sits near $1,569, so the government number is roughly 29% above what units really rent for.

That gap is normal because in other metros the HUD figure lands well below market rent, which is the part most people don't expect when they go looking up Fair Market Rent for their own county.

Fair Market Rent is set at the 40th percentile of local rents

Fair Market Rent, shortened to FMR almost everywhere, is a dollar figure the US Department of Housing and Urban Development publishes once a year for every metro area and every county in the country, broken out by bedroom count.

HUD sets it at roughly the 40th percentile of rents for standard-quality units in that area, and the 40th percentile means 40 of every 100 such units rent for less than the figure while the other 60 rent for more. So it's deliberately below the middle of the local market.

Standard quality leaves out brand-new buildings, public housing, and units in poor condition, and the underlying numbers describe what people already living in those units pay each month. Listing sites show something else, which is what landlords are asking right now, and the two move on different clocks.

Vouchers are where a renter actually meets the number

The main job FMR does is set the payment standard for the Housing Choice Voucher program, the federal rental-assistance program most people still call Section 8, and a payment standard is the ceiling a local housing authority will count toward your rent.

A household with a voucher generally pays about 30% of its income toward rent while the housing authority covers the rest up to that ceiling, so where the ceiling sits decides which apartments are within reach. The ceiling does most of the work here.

HUD also uses FMR to set limits in several other programs it runs, and local housing authorities can move their own payment standard anywhere from 90% to 110% of the published figure without special permission, so the number in HUD's table isn't always the number your local office applies.

The difference runs both ways and it gets large in both directions

We measure market rent with ZORI, the Zillow Observed Rent Index, which tracks what the same set of homes rents for over time so the number doesn't lurch every time a batch of luxury buildings opens. Our dataset also carries HUD-derived bedroom-level figures, and lining the two up shows how far they drift.

A plus sign below means the HUD-derived figure sits above market rent, and a minus sign means it sits below.

Market rent in Phoenix and New York sit at opposite ends of that list, and both gaps are wide enough to change which apartments a voucher can cover. The direction flips by metro.

Lagged survey data is why the two numbers separate

FMR comes out of a formula built on Census survey data that's already a couple of years old by the time HUD publishes it, then pushed forward with adjustment factors, while market rent is simply what landlords are asking this month. The lag is the whole mechanism.

So in a metro where rents spiked and then cooled off, the formula can still be climbing toward the spike after asking rents have already settled back down. In a metro where rents keep rising year after year, the formula trails behind and the published figure ends up well under what units go for.

Houston and Philadelphia land within about 1% either way, which is what happens when local rent growth has been steady enough for the lagged data to keep pace. The same kind of lag separates private rent estimates from each other, and we broke that down in why rent estimates differ.

A figure below market rent makes the voucher search harder

Where FMR sits under market rent, the ceiling doesn't stretch to what landlords are asking, so searches run longer and the units that do fit tend to cluster into fewer neighborhoods. Housing authorities can request exception payment standards for high-cost areas, though they have to apply and get HUD to sign off on it.

Where FMR sits above market rent, as in Phoenix, the ceiling has room in it relative to what units actually rent for, which widens the set of landlords who can accept a voucher at the standard rate.

Look up your own county before you rely on any figure here

The values in our table are HUD-derived numbers inside the RentDataNow dataset, and they aren't the official published FMR for those areas. Anyone who needs the legally operative number, whether that's a voucher ceiling or a program limit, should pull it straight from HUD's Fair Market Rent tables.

Search that page by state and county, pick your bedroom count, and check the fiscal year printed at the top, since new values take effect each October. Then pull the current market rent for the same city and set the two figures side by side before you assume either one describes what you'll pay.

Sources

• Code of Federal Regulations, 24 CFR 888.113, Fair Market Rent methodology

• HUD User, Fair Market Rent documentation system

• RentDataNow city rent data (Zillow Observed Rent Index) and HUD-derived bedroom-level figures