Austin to San Antonio distance

Austin to San Antonio by road

The fastest driving route is 79.2 miles (127 km) long and takes about 1 hr 30 min without stops or traffic. Almost all of it is on I-35: 77.0 mi of 79.2 mi.

The whole route stays in Texas. That’s an average of 53 mph (85 km/h), and at under two hours you can do it without stopping. 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, Austin and San Antonio are 73.5 miles (118 km) apart. That’s the geodesic on the WGS84 ellipsoid, the distance “as the crow flies”.

The road is 8% longer: for every 100 miles in a straight line you drive 108. The route runs almost straight. Of the 40 US pairs in this series, it ranks 36th for detour (the average is 14%).

From Austin, San Antonio lies to the southwest (bearing 218°), and from San Antonio, Austin lies to the northeast.

Halfway between Austin and San Antonio

Halfway along the straight line, 36.8 miles (59.1 km) from each city, is the point 29.8462° N, 98.1199° W. It falls near Spring Branch (Texas, pop. 267), 17.5 mi away.

By road, the halfway point is 39.6 miles (63.7 km) from each city, near Staples (Texas, pop. 185), 12.8 mi away. The two midpoints are 6.9 mi apart: if you want to meet halfway, the one on the road is the useful one.

Time zone

Austin and San Antonio share the same time all year: both are on Central Time.

The two cities

Austin sits at 487 ft (148 m) and San Antonio at 649 ft (198 m), 162 ft (49 m) higher.

Austin has 1.0 million people and San Antonio 1.5 million people (Census Bureau estimate for 2025).