For ZIP 78666 in San Marcos, TX, the decision question is how to read a current typical asking-rent benchmark alongside bedroom sizing, household measures, and housing-stock composition—not as a quote for a particular home. Zillow’s June 2026 ZIP-level ZORI is $1,395 per month, down 2.13% year over year. This is a typical observed asking-rent index blended across rental types, so it is a market reference rather than a unit-specific advertised price. The five-digit label is both a Zillow ZIP market identifier and a matched Census ZCTA; a ZCTA is a statistical area and is not identical to a USPS delivery ZIP. That geographic distinction matters because statistical reporting and delivery boundaries are not the same thing.
The bedroom pattern translates the ZIP index into relative size tiers. The modelled monthly ZIP estimates for a studio, one, two, three, and four bedrooms are $1,103, $1,178, $1,395, $1,772, and $2,074, respectively. These values scale ZIP ZORI using the local HUD ladder; they are modelled estimates, never measured bedroom rents. The local FY2026 HUD standards put a two-bedroom benchmark at $1,480 and a four-bedroom benchmark at $2,200. HUD FMR/SAFMR is an administrative bedroom-specific standard, not asking rent. Accordingly, the two-bedroom model matches the ZIP index by construction, while the steps between bedroom sizes reflect the HUD ladder rather than observed bedroom-specific listings.
Income and renter-burden measures describe the matched ACS 2024 five-year ZCTA survey rather than current applicants. Median household income is $54,737, with a $3,230 margin of error. Annual income associated with paying the ZIP index at 30% of income is $55,800. This 30% required-income screen is arithmetic, not advice or an applicant qualification rule. Renter-occupied homes account for 61.9% of occupied housing, and the ACS estimate shows 12,445 renter households spending 30% or more of income on gross rent, equal to 59.2% of renter households. These are aggregate household measures; they do not establish a particular renter’s income, expenses, or eligibility for a specific property.
Housing stock supplies a separate view of the setting in which asking rents are observed. The ZCTA has 36,580 housing units and a 7.2% vacancy rate. Of vacant units, 1,108 are classified as for rent, while 224 are for sale and 57 are seasonal. The structure mix includes 15,816 single-family units and 8,360 large-multifamily units. These categories describe survey-period housing inventory and broad structure types, not current condition, lease status, price, or availability at any individual address. In particular, a unit counted vacant for rent is not proof that it is presently advertised, ready to occupy, or priced near the ZIP index.
The rent measures require separate interpretation rather than a blended conclusion. Zillow ZORI is the ZIP-level typical observed asking-rent index. ACS median gross rent is $1,319, with a $39 margin of error; it is a five-year survey measure of occupied renter homes and includes selected utilities. The ACS figure is 5.8% below the Zillow index, but that numerical difference does not create a like-for-like asking-rent gap because the universes, timing, occupancy basis, and utility treatment differ. As a separate arithmetic comparison, the $1,395 ZIP index equals 94.3% of the local two-bedroom HUD standard. That comparison does not convert HUD FMR/SAFMR into a market asking-rent observation.
Wider geography provides context without replacing the ZIP evidence. The City of San Marcos context has $1,408.31 rent and a 69.2% renter share; the Hays County context has $1,571 rent and a 35.9% renter share; and the Austin-Round Rock-Georgetown, TX metro context has $1,653 rent and 9.5% apartment vacancy. Each is a city, county, or metro scope rather than the ZIP market identifier or matched ZCTA. The differences show that wider-area rent, tenure, and apartment-vacancy measures operate at broader geographic scopes, with their own definitions, and should be treated as context rather than as substitutes for the ZIP-level ZORI or ZCTA survey estimates.
Important limits remain at the property level. ZORI does not supply a quoted rent, bedroom count, utility bill, concession, availability date, or lease term for a particular unit. ACS carries sampling uncertainty and describes occupied renter homes, while HUD standards are administrative benchmarks and the ZCTA is not an exact USPS delivery ZIP. A property-level review would need the advertised rent, confirmed bedroom designation, lease duration, included and separately billed utilities, recurring fees, deposits, availability status, and the property’s stated screening terms. Neither aggregate vacancy nor observed renter burden can prove the affordability, vacancy, or suitability of any particular unit.
","findings":[{"body":"In June 2026, ZIP 78666’s Zillow ZORI was $1,395 per month, 2.13% below its year-earlier level. It is Zillow’s ZIP-level typical observed asking-rent index blended across rental types. The figure is a market benchmark, not a recorded lease price, advertised rent, utility bill, concession, or availability statement for a specific property.","title":"ZIP asking-rent benchmark"},{"body":"The studio through four-bedroom figures of $1,103, $1,178, $1,395, $1,772, and $2,074 are modelled monthly ZIP estimates. They scale the ZIP ZORI using the local HUD bedroom ladder. HUD FMR/SAFMR values are administrative bedroom-specific standards, so the resulting series describes relative sizing rather than measured rents for available apartments or houses.","title":"Bedroom figures are modelled, not observed"},{"body":"Matched-ZCTA ACS estimates median household income at $54,737 and estimates that 59.2% of renter households spend at least 30% of income on gross rent. The $55,800 required-income figure is annualized rent arithmetic only. ACS gross rent includes selected utilities and covers occupied renter homes, preventing a direct equivalence with Zillow’s asking-rent index.","title":"ACS signals show aggregate renter pressure"},{"body":"The ACS vacancy rate is 7.2%, including 1,108 units classified vacant for rent, but those survey categories do not establish current openings at a given property. Wider context rent is $1,408.31 in the City of San Marcos, $1,571 in Hays County, and $1,653 in the Austin-Round Rock-Georgetown metro; each is contextual rather than ZIP-specific.","title":"Stock and wider geography require scope discipline"}],"risks":["The Zillow figure blends rental types and reflects a typical observed asking-rent index, so it cannot establish the advertised rent, concessions, utilities, availability, or condition of a specific unit.","The Census ZCTA is statistical geography rather than an exact USPS delivery ZIP, and ACS values are survey estimates with margins of error, not a transaction-level record.","HUD FMR/SAFMR values are administrative bedroom-specific standards, while the bedroom series merely scales ZORI by that ladder; neither source measures current bedroom-specific listings.","Vacancy categories and renter burden are aggregate observations; they cannot demonstrate that any given property is vacant, affordable, occupied by a burdened renter, or suitable."],"qa":[{"a":"The $1,395 figure is Zillow’s June 2026 ZIP-level ZORI, defined here as a typical observed asking-rent index blended across rental types. Its 2.13% year-over-year decline describes movement in that index. It does not identify a property, quoted lease rent, utility obligation, concession, or contemporaneously vacant unit.","q":"What does the $1,395 ZIP rent figure represent?"},{"a":"The bedroom values are modelled estimates created by scaling the ZIP ZORI with the local HUD bedroom ladder. They preserve relative studio-through-four-bedroom differences embedded in HUD standards. Because HUD FMR/SAFMR is an administrative benchmark rather than asking-rent evidence, the outputs are not measured bedroom rents or listing averages.","q":"How were the bedroom estimates created?"},{"a":"No. The $55,800 figure results from annualizing the ZIP ZORI and applying a 30% income share. It is an arithmetic affordability screen, not advice, underwriting guidance, or an applicant qualification rule. Actual property screening can use different income definitions, household arrangements, fees, and documentation requirements.","q":"Does the $55,800 income figure describe an approval requirement?"},{"a":"San Marcos city, Hays County, and the Austin-Round Rock-Georgetown metro are wider geographic scopes with their own context measures. Their rent, renter-share, and vacancy values can frame the ZIP result, but they do not change the ZIP-level Zillow index or the matched-ZCTA ACS survey estimates into the same evidence universe.","q":"Why should city, county, and metro figures not replace ZIP results?"}],"sources":[{"key":"apartment_list_time_on_market","name":"Apartment List Time on Market — listing liquidity","release":"Apartment List 2026-07","pulledAt":"2026-08-08","url":"https://www.apartmentlist.com/research/category/data-rent-estimates"},{"key":"apartment_list_vacancy","name":"Apartment List Vacancy Index — rental vacancy","release":"Apartment List 2026-07","pulledAt":"2026-08-08","url":"https://www.apartmentlist.com/research/apartment-list-vacancy-index-methodology"},{"key":"census_zcta_facts","name":"Census ACS five-year — ZCTA housing and income","release":"ACS 2024 5-year ZCTA","pulledAt":"2026-08-08","url":"https://api.census.gov/data/2024/acs/acs5.html"},{"key":"hud_zip","name":"HUD USPS crosswalk and Small Area FMRs — ZIP rent fallback","release":"ZIP-CBSA 2025Q4 + SAFMR FY2026","pulledAt":"2026-07-26","url":"https://www.huduser.gov/portal/datasets/usps_crosswalk.html"},{"key":"realtor_county","name":"Realtor.com Economic Research — county listing inventory","release":"county inventory 2026-06","pulledAt":"2026-07-28","url":"https://www.realtor.com/research/data/"},{"key":"redfin","name":"Redfin Data Center — inventory, days on market, and price cuts","release":"metro tracker through 2026-05-01","pulledAt":"2026-07-26","url":"https://www.redfin.com/news/data-center/"},{"key":"redfin_zip","name":"Redfin Data Center — ZIP resale activity and supply","release":"ZIP rolling 3 months through 2026-06-30; updated 2026-07-03","pulledAt":"2026-08-12","url":"https://www.redfin.com/news/data-center/"},{"key":"zillow_county","name":"Zillow ZHVI and ZORI — county values and rents","release":"county ZHVI/ZORI 2026-06","pulledAt":"2026-07-26","url":"https://www.zillow.com/research/data/"},{"key":"zillow_zori","name":"Zillow ZORI — metro market rents","release":"Metro_zori_uc_sfrcondomfr_sm_sa_month.csv","pulledAt":"2026-07-26","url":"https://www.zillow.com/research/data/"},{"key":"zillow_zori_city","name":"Zillow ZORI — city market rents","release":"zillow_zori_city.csv","pulledAt":"2026-07-29","url":"https://www.zillow.com/research/data/"},{"key":"zillow_zori_zip","name":"Zillow ZORI — ZIP market rents","release":"ZORI ZIP 2026-06","pulledAt":"2026-08-08","url":"https://www.zillow.com/research/data/"}],"history":[{"period":"2016-03-01","rent":1054.961126},{"period":"2016-04-01","rent":1063.557908},{"period":"2016-05-01","rent":1060.604492},{"period":"2016-06-01","rent":1054.616582},{"period":"2016-07-01","rent":1056.184438},{"period":"2016-08-01","rent":1070.937464},{"period":"2016-09-01","rent":1086.805161},{"period":"2016-10-01","rent":1102.087736},{"period":"2016-11-01","rent":1086.267131},{"period":"2016-12-01","rent":1071.200994},{"period":"2017-01-01","rent":1069.80105},{"period":"2017-02-01","rent":1069.868004},{"period":"2017-03-01","rent":1085.264033},{"period":"2017-04-01","rent":1077.249924},{"period":"2017-05-01","rent":1084.524044},{"period":"2017-06-01","rent":1086.573475},{"period":"2017-07-01","rent":1091.447158},{"period":"2017-08-01","rent":1083.762108},{"period":"2017-09-01","rent":1084.989843},{"period":"2017-10-01","rent":1079.135035},{"period":"2017-11-01","rent":1110.345995},{"period":"2017-12-01","rent":1114.20426},{"period":"2018-01-01","rent":1113.509659},{"period":"2018-02-01","rent":1094.847844},{"period":"2018-03-01","rent":1106.929844},{"period":"2018-04-01","rent":1116.572024},{"period":"2018-05-01","rent":1121.03333},{"period":"2018-06-01","rent":1119.56619},{"period":"2018-07-01","rent":1122.368773},{"period":"2018-08-01","rent":1132.343457},{"period":"2018-09-01","rent":1141.582159},{"period":"2018-10-01","rent":1129.972288},{"period":"2018-11-01","rent":1120.841297},{"period":"2018-12-01","rent":1133.064904},{"period":"2019-01-01","rent":1152.96315},{"period":"2019-02-01","rent":1171.527563},{"period":"2019-03-01","rent":1162.592869},{"period":"2019-04-01","rent":1166.022047},{"period":"2019-05-01","rent":1168.045202},{"period":"2019-06-01","rent":1177.160808},{"period":"2019-07-01","rent":1180.51494},{"period":"2019-08-01","rent":1181.519037},{"period":"2019-09-01","rent":1178.109669},{"period":"2019-10-01","rent":1194.399211},{"period":"2019-11-01","rent":1196.288213},{"period":"2019-12-01","rent":1195.186775},{"period":"2020-01-01","rent":1186.664919},{"period":"2020-02-01","rent":1187.237413},{"period":"2020-03-01","rent":1202.936725},{"period":"2020-04-01","rent":1190.093496},{"period":"2020-05-01","rent":1182.196646},{"period":"2020-06-01","rent":1179.888161},{"period":"2020-07-01","rent":1189.31969},{"period":"2020-08-01","rent":1201.725261},{"period":"2020-09-01","rent":1212.589715},{"period":"2020-10-01","rent":1211.493361},{"period":"2020-11-01","rent":1216.224024},{"period":"2020-12-01","rent":1217.371437},{"period":"2021-01-01","rent":1222.494533},{"period":"2021-02-01","rent":1223.018733},{"period":"2021-03-01","rent":1223.455973},{"period":"2021-04-01","rent":1242.969907},{"period":"2021-05-01","rent":1262.682472},{"period":"2021-06-01","rent":1291.67194},{"period":"2021-07-01","rent":1307.538583},{"period":"2021-08-01","rent":1326.868737},{"period":"2021-09-01","rent":1338.884349},{"period":"2021-10-01","rent":1365.753944},{"period":"2021-11-01","rent":1383.262917},{"period":"2021-12-01","rent":1399.40707},{"period":"2022-01-01","rent":1408.079496},{"period":"2022-02-01","rent":1429.493241},{"period":"2022-03-01","rent":1447.54312},{"period":"2022-04-01","rent":1462.431647},{"period":"2022-05-01","rent":1468.40682},{"period":"2022-06-01","rent":1466.126735},{"period":"2022-07-01","rent":1468.256555},{"period":"2022-08-01","rent":1475.572976},{"period":"2022-09-01","rent":1499.16812},{"period":"2022-10-01","rent":1505.488367},{"period":"2022-11-01","rent":1506.03431},{"period":"2022-12-01","rent":1508.222282},{"period":"2023-01-01","rent":1512.981252},{"period":"2023-02-01","rent":1518.550813},{"period":"2023-03-01","rent":1516.368099},{"period":"2023-04-01","rent":1511.511391},{"period":"2023-05-01","rent":1505.449207},{"period":"2023-06-01","rent":1497.616611},{"period":"2023-07-01","rent":1495.947803},{"period":"2023-08-01","rent":1494.928553},{"period":"2023-09-01","rent":1494.936038},{"period":"2023-10-01","rent":1495.049023},{"period":"2023-11-01","rent":1505.978059},{"period":"2023-12-01","rent":1504.511417},{"period":"2024-01-01","rent":1521.026842},{"period":"2024-02-01","rent":1512.426084},{"period":"2024-03-01","rent":1524.268597},{"period":"2024-04-01","rent":1514.004878},{"period":"2024-05-01","rent":1509.561827},{"period":"2024-06-01","rent":1506.989657},{"period":"2024-07-01","rent":1496.807435},{"period":"2024-08-01","rent":1498.629597},{"period":"2024-09-01","rent":1484.401955},{"period":"2024-10-01","rent":1473.872985},{"period":"2024-11-01","rent":1453.394523},{"period":"2024-12-01","rent":1450.784736},{"period":"2025-01-01","rent":1420.867842},{"period":"2025-02-01","rent":1416.587339},{"period":"2025-03-01","rent":1401.600938},{"period":"2025-04-01","rent":1408.672929},{"period":"2025-05-01","rent":1417.333423},{"period":"2025-06-01","rent":1425.804367},{"period":"2025-07-01","rent":1429.832465},{"period":"2025-08-01","rent":1423.23531},{"period":"2025-09-01","rent":1424.058175},{"period":"2025-10-01","rent":1424.287691},{"period":"2025-11-01","rent":1427.844247},{"period":"2025-12-01","rent":1423.363919},{"period":"2026-01-01","rent":1430.553185},{"period":"2026-02-01","rent":1429.130068},{"period":"2026-03-01","rent":1427.883333},{"period":"2026-04-01","rent":1419.761771},{"period":"2026-05-01","rent":1407.879237},{"period":"2026-06-01","rent":1395.441018}],"historySummary":{"pointCount":124,"firstPeriod":"2016-03-01","latestPeriod":"2026-06-01","coverageMonths":124,"coverageRatio":1,"changes":{"1":{"years":1,"startPeriod":"2025-06-01","endPeriod":"2026-06-01","startRent":1425.804367,"endRent":1395.441018,"change":-0.021295592651246253,"cagr":-0.021295592651246253},"3":{"years":3,"startPeriod":"2023-06-01","endPeriod":"2026-06-01","startRent":1497.616611,"endRent":1395.441018,"change":-0.06822546721872591,"cagr":-0.023279554718257933},"5":{"years":5,"startPeriod":"2021-06-01","endPeriod":"2026-06-01","startRent":1291.67194,"endRent":1395.441018,"change":0.08033702272730348,"cagr":0.015574650187824446}},"maxDrawdown":-0.08451763636248422,"annualizedVolatility":0.02971700063975512,"consecutiveReturnCount":123}}