Houston to San Antonio distance
Houston and San Antonio are 190 miles (306 km) apart in a straight line and 195 miles (314 km) apart by road: about 3 hr 30 min of driving without stops, mostly on I-10. Below you’ll find the route map, both halfway points, the bearing and where every figure comes from.
By the Mapsfera Team
- By road
- 195 mi (314 km)
- Driving time
- 3 hr 30 min
- Straight line
- 190 mi (306 km)
- Driving route
- Straight line
- Straight-line midpoint
- Halfway by road
Lambert azimuthal equal-area projection centered on the midpoint. Route: FOSSGIS OSRM with data © OpenStreetMap contributors, calculated on October 31, 2026; simplified line.
The figures
| Figure | Value |
|---|---|
| Straight line | 190 mi (306 km) geodesic on the WGS84 ellipsoid |
| By road | 195 mi (314 km) fastest driving route (OSRM) |
| Driving time | 3 hr 30 min no stops, no traffic |
| Road detour | +3% 1.03 times the straight line |
| Average speed | 56 mph (90 km/h) along the route, without stops |
| Bearing | 264° (west) leaving Houston toward San Antonio |
| Midpoint | 29.6029° N, 96.9311° W near Moulton (Texas) |
| Halfway by road | Near Moulton (Texas) 97.5 mi from each city by road |
| Time difference | None both share the same time |
| Elevation | Houston: 36 ft (11 m) · San Antonio: 649 ft (198 m) USGS 3DEP |
| Population | Houston: 2,397,315 · San Antonio: 1,548,422 Census Bureau estimate for 2025 |
Houston to San Antonio by road
The fastest driving route is 195 miles (314 km) long and takes about 3 hr 30 min without stops or traffic. Almost all of it is on I-10: 186 mi of 195 mi.
The whole route stays in Texas. That’s an average of 56 mph (90 km/h). AAA recommends a break every two hours or 100 miles: with 1 stop of 20 minutes, the trip takes about 3 hr 50 min. The time is OSRM’s estimate with OpenStreetMap data: no traffic and speeds somewhat below the limits, so real trips can differ.
Straight-line distance and bearing
In a straight line, the shortest distance over the Earth’s surface, Houston and San Antonio are 190 miles (306 km) apart. That’s the geodesic on the WGS84 ellipsoid, the distance “as the crow flies”.
The road is 3% longer: for every 100 miles in a straight line you drive 103. The route runs almost straight. Of the 40 US pairs in this series, it has the smallest detour (the average is 14%).
From Houston, San Antonio lies to the west (bearing 264°), and from San Antonio, Houston lies to the east.
Halfway between Houston and San Antonio
Halfway along the straight line, 94.9 miles (153 km) from each city, is the point 29.6029° N, 96.9311° W. It falls near Moulton (Texas, pop. 847), 13.2 mi away. The nearest town of 20,000 people or more is Sienna (Texas, pop. 24,992), 86.2 mi away.
By road, the halfway point is 97.5 miles (157 km) from each city, near Moulton (Texas, pop. 847), 14.6 mi away. The nearest town of 20,000 people or more is Sienna (Texas, pop. 24,992), 87.7 mi away. The two midpoints almost coincide (6.0 mi apart), because the road doesn’t stray far from the straight line.
Time zone and flight
Houston and San Antonio share the same time all year: both are on Central Time.
No flight time is given: under 500 km (311 miles) in a straight line, time at the airport outweighs time in the air.
The two cities
Houston sits at 36 ft (11 m) and San Antonio at 649 ft (198 m), 613 ft (187 m) higher.
Houston has 2.4 million people and San Antonio 1.5 million people (Census Bureau estimate for 2025).
Frequently asked questions
How many miles is it from Houston to San Antonio?
190 miles (306 km) in a straight line and 195 miles (314 km) by road on the fastest route (mostly on I-10).
How long is the drive from Houston to San Antonio?
About 3 hr 30 min without stops or traffic, according to OSRM with OpenStreetMap data; with 1 stop of 20 minutes, about 3 hr 50 min.
Where is the halfway point between Houston and San Antonio?
In a straight line, near Moulton (Texas). By road, 97.5 mi from each city, near Moulton (Texas).
Are Houston and San Antonio in the same time zone?
Yes: both are on Central Time all year.
Which city is higher, Houston or San Antonio?
San Antonio, at 649 ft (198 m); Houston sits at 36 ft (11 m).
Measure it yourself on the map
The same two cities, already set up in the tools: move the points, get the route by bike or on foot and download the map.
- Distance between two points Measure the distance between any two places or points on the map, in miles or kilometers.
- Straight line vs driving distance Compare the as-the-crow-flies distance with the real driving distance and see how much the road adds.
- Halfway point Find the exact halfway point between two places and see it on the map, ready to share.
More distances from Houston
All distancesMore distances from San Antonio
Sources
- Driving route: FOSSGIS OSRM, car profile (calculated on October 31, 2026) · FOSSGIS e.V.
- Roads, streets and places · © OpenStreetMap contributors (ODbL)
- Straight line, bearings and midpoint (geodesics on the WGS84 ellipsoid) · GeographicLib (C. F. F. Karney)
- US city centers (GNIS) and their elevation (3DEP) · USGS (public domain)
- Population estimates, Vintage 2025 · US Census Bureau (public domain)
- Places near the midpoints: Mapsfera gazetteer (GeoNames, INE, IGN and Census) · Mapsfera
- Time zones (timezone-boundary-builder outlines and the IANA database) · © OpenStreetMap contributors (ODbL)
- Map: provinces (IGN), states (US Census Bureau) and countries (Natural Earth) · IGN, Census and Natural Earth
- Methodology