Small Area Fair Market Rents (SAFMRs) are FMRs calculated for ZIP Codes within Metropolitan Areas. Small Area FMRs are required to be used to set Section 8 Housing Choice Voucher payment standards in areas designated by HUD.

They are created at ZIP Code Tabulation Areas (ZCTAs), which are areas that approximate ZIP code boundaries, though the two are distinctly different. Actual zip codes that are not included in the ZCTA database are added to the Small Area FMR database. To show all these areas, the data is displayed on a ZCTA code map, which does not match the Zip Code map. Due to this difference in geographies, users should be cautious interpreting the map.

In metropolitan areas, HUD defines Small Areas using ZIP Codes within the metropolitan area. Using ZIP codes as the basis for FMRs provides tenants with greater ability to move into "Opportunity Neighborhoods" with jobs, public transportation, and good schools. They also provide for multiple payment standards within a metropolitan area, and they are likely to reduce need for extensive market area rent reasonableness studies. Lastly, HUD hopes that setting FMRs for each ZIP code will reduce overpayment in lower-rent areas.