ZIP code 78666: San Marcos, TX
78666 is a ZIP code in San Marcos, Texas, mainly in Hays County, part of the Austin-Round Rock-San Marcos, TX metro area. About 88,583 people live here.
- Population
- 88,583
- Median household income
- $54,737
- Typical home value
- $309,400-2.9% in 12 months
- Median rent
- $1,319gross, per month
- Median age
- 26.9
- Homeowners
- 38.1%of occupied homes
Shaded: ZIP code 78666's area. Click anywhere on the map to see which ZIP code it's in.
ZIP codes within 10 milesWithin 25 miles
ZIP code 78666 details
| City | San Marcos |
|---|---|
| State | Texas |
| County | Hays County (also partly Guadalupe County, Comal County, Caldwell County) |
| Metro area | Austin-Round Rock-San Marcos, TX |
| Time zone | Central Time (UTC−6), observes daylight saving time |
| Type | Standard (delivery area) |
| Land area | 192.4 sq mi, plus 1 sq mi of water |
| Population density | 461 people per sq mi |
| Bachelor's degree or higher | 35.7% of adults 25+ |
| Average commute | 25.5 minutes |
| Center coordinates | 29.88166, -97.98479 |
Median rent in 78666 by bedrooms
| Size | Median gross rent |
|---|---|
| Studio | $1,296/mo |
| 1 bedroom | $1,227/mo |
| 2 bedrooms | $1,371/mo |
| 3 bedrooms | $1,601/mo |
| 4 bedrooms | $967/mo |
Gross rent includes utilities paid by the tenant. ACS 2020–2024; sizes with too few rentals to estimate are left out.
ZIP codes near 78666
| ZIP code | City | Distance | Population |
|---|---|---|---|
| 78655 | Martindale, TX | 10.1 mi | 3,730 |
| 78656 | Maxwell, TX | 10.7 mi | 2,847 |
| 78670 | Staples, TX | 11.5 mi | 130 |
| 78667 | San Marcos, TX | 12.0 mi | — |
| 78640 | Kyle, TX | 12.5 mi | 77,531 |
| 78130 | New Braunfels, TX | 13.9 mi | 104,009 |
| 78622 | Fentress, TX | 14.1 mi | 331 |
| 78623 | Fischer, TX | 14.8 mi | 1,645 |
Population and median household income: ACS 2020–2024 5-year estimates. Typical home value: Zillow Home Value Index (September 2026) where available, otherwise the ACS median owner-reported value. "PO Box" marks ZIP codes with no delivery area of their own. Methodology
Buying a home in 78666?
A typical home in ZIP code 78666 is worth about $309,400 (Zillow Home Value Index). The median household here earns $54,737 a year. See what buying here would cost per month, with Texas average taxes and insurance filled in.
Monthly payment for a $309,400 homeWhat can a $54,737 income afford?Rental property numbers
About ZIP code 78666
What city is ZIP code 78666?
ZIP code 78666 is in San Marcos, TX, in Hays County.
What county is ZIP code 78666 in?
78666 is mainly in Hays County, Texas, and partly in Guadalupe County, Comal County and Caldwell County.
What is the population of ZIP code 78666?
About 88,583 people live in ZIP code 78666, according to the American Community Survey 2020–2024 5-year estimates.
What time zone is ZIP code 78666 in?
78666 is in Central Time (UTC−6). It observes daylight saving time.
What other ZIP codes does San Marcos have?
San Marcos, TX also uses 78667.