How rent estimates work: HUD Fair Market Rents vs. Census medians

Source 1: HUD Fair Market Rents

The U.S. Department of Housing and Urban Development publishes Fair Market Rents (FMRs) every year, for every county or metro area, by bedroom count from studio to four bedrooms. HUD uses them to set housing voucher payments, so they're designed to describe a modest, standard-quality rental: specifically, the 40th percentile rent paid by recent movers. Four in ten such rentals cost less, six in ten cost more.

In many metro areas HUD also publishes Small Area Fair Market Rents (SAFMRs) for individual ZIP codes, because rents can vary a lot within one metro. New FMRs take effect each October 1.

Things to keep in mind:

• The 40th percentile sits below the middle of the market, by design.
• A county FMR covers every neighborhood in the county, expensive and cheap alike.
• FMRs are based on survey data that is a couple of years old, which HUD adjusts forward with inflation factors.

Source 2: Census median gross rent

The Census Bureau's American Community Survey (ACS) asks households what they pay. Its 5-year estimates report the median gross rent by bedroom count for each ZIP Code Tabulation Area, a close match to a ZIP code. Half of renters pay more, half pay less.

• It covers all renters, including people who signed their lease years ago at a lower rent, so it usually runs below what a new tenant would pay today.
• It pools five years of surveys, so it lags in fast-rising markets.
• Each figure comes with a margin of error. In small ZIP codes the sample can be thin and the error wide.
• Medians of $3,500 or more are reported only as “$3,500+”, so in expensive areas the Census figure is a floor, not a value.

Gross rent, not contract rent

Both sources use gross rent: the rent plus the utilities the tenant pays. If you own a property where tenants pay their own electricity and gas, the rent you can charge will typically be somewhat lower than a gross-rent figure. If you pay utilities for your tenants, gross rent is closer to what you collect, but those utilities are then your expense.

How YieldBadger combines them

For each ZIP code and bedroom count, the rent estimator shows a range built only from published figures. Nothing is padded or invented:

1. Start with the ZIP-level figures: HUD's Small Area FMR (where HUD publishes one) and the Census median gross rent. Census estimates whose margin of error is more than half the value are left out as too uncertain.
2. If there are two ZIP-level figures, the range runs from the lower to the higher one.
3. If there's only one, the county FMR becomes the second point of the range, as the most honest comparison available.
4. If there are none, the county FMR is shown on its own and labeled as a county estimate.
5. The single best guess is the average of the ZIP-level figures, or the county figure when that's all there is.

Every figure is shown with its source and date, so you can see exactly where the range came from. City and state pages summarize the same ZIP-level ranges across all the ZIP codes in the area.

How to use a rent estimate well

• Treat it as a sanity check, not an appraisal. A renovated unit with parking and in-unit laundry can rent well above the range; a dated one, below it.
• Compare with current listings of similar units nearby. If listings are far above the range, find out why before you rely on them.
• Be conservative in your underwriting. Rent drives every other number: NOI, cash flow, DSCR and the 1% rule. Testing a rent at the low end of the range shows how much room for error a deal has.

The calculators' “Fill with local data” box uses the same best guess for the bedroom count you choose, along with the local property tax estimate and current mortgage rate. The full list of sources is on the data sources page.