How far is Killeen, TX from San Marcos, TX?
The driving distance from Killeen, TX to San Marcos, TX is about 97.1 miles (156.3 km), with a travel time of about 01h 51m by car.
- The straight-line flight distance is about 86.2 miles (138.7 km).
- For a round trip, plan for roughly 03h 42m of driving time before adding stops, traffic, or weather delays.
- A comfortable departure window is usually 8:00 AM to 10:00 AM CDT.
Reverse, save, or send this route
This route works well as a day trip with time at the destination. Copy the route link, send it to another device, or print a clean version before you head out.
This route works well as a day trip with time at the destination.
Flight Distance
Driving Distance
Gas Cost Calculator
Leave and Arrive Planner
Pick a departure time to see your estimated arrival and same-day return window.
Drive time stays fixed at 01h 51m.
A morning start gives you useful time at the destination and keeps the return out of the late evening.
You are leaving earlier than the recommended window, which gives you extra margin for breaks and traffic.
Halfway Point
A useful midpoint for breaks, coffee, or meeting in the middle.
The fourth most populous city in Williamson County, Texas.
Route Weather Snapshot
Check the forecast at both ends before you head out.
Partly Sunny
Slight Chance Rain Showers
Driving Route Map
The map below follows the saved road route between Killeen and San Marcos.
Turn-by-Turn Driving Directions
Step-by-step road directions between Killeen and San Marcos.
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1
Start on the route
23 m · 11 sec
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2
Turn left
25 m · 8 sec
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3
Turn right onto East Veterans Memorial Boulevard
1.5 km · 2 min · East Veterans Memorial Boulevard
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4
Turn left onto South Fort Hood Street
33.8 mi · 38 min · South Fort Hood Street
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5
Take the exit slight right
999 ft · 17 sec
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6
Continue on North Interstate 35
1035 ft · 16 sec · North Interstate 35
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7
Continue on North Interstate 35
2999 ft · 47 sec · North Interstate 35
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8
Take the ramp slight left toward I 35 South: Austin
1852 ft · 45 sec
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9
Merge slight left onto Purple Heart Trail
27.9 mi · 30 min · Purple Heart Trail
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10
Keep slight left to continue on Purple Heart Trail
31 mi · 35 min · Purple Heart Trail
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11
Take the exit slight right toward TX 80 East, TX 142 East, TX 21 East: Bastrop, Luling
1079 ft · 26 sec
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12
Turn straight onto North Interstate 35
3250 ft · 1 min · North Interstate 35
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13
Turn slight right
144 m · 17 sec
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14
Turn slight right onto East Hopkins Street
1.1 mi · 2 min · East Hopkins Street
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15
Turn right onto North LBJ Drive
64 m · 9 sec · North LBJ Drive
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16
Turn left
128 m · 36 sec
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17
At the end of the road, turn left onto North Guadalupe Street
43 m · 3 sec · North Guadalupe Street
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18
Arrive at your destination
0 m · 1 sec · North Guadalupe Street
Car Route Details
A richer read on the saved driving route between Killeen and San Marcos.
Straightforward drive
The saved road route has a manageable number of maneuvers and should be easy to follow with normal attention to signs.
South Fort Hood Street
Turn left onto South Fort Hood Street
33.8 mi · 00h 38m
Route Summary
A quick read on whether this route feels easy, ambitious, or worth planning around.
A comfortable day-trip route
This route works well as a day trip. You can leave in the morning, spend meaningful time at the destination, and still return the same day.
Partly Sunny leaving Killeen and Slight Chance Rain Showers near San Marcos.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from Killeen to San Marcos?
The road trip is about 97.1 miles (156.3 km) and usually takes 01h 51m in normal driving conditions.
Is this a same-day trip or an overnight route?
This route works well as a day trip. You can leave in the morning, spend meaningful time at the destination, and still return the same day.
What is the halfway point on this route?
Round Rock is a useful midpoint, sitting about 48.7 miles from Killeen and 48.5 miles from San Marcos.
How much longer is the road route than the straight-line distance?
The direct path is about 86.2 miles (138.7 km), while the road route adds roughly 10.9 extra miles because roads do not follow the straight air line.
When is the best time to leave for this route?
A good departure window is usually 8:00 AM to 10:00 AM CDT. If you want a more comfortable same-day return, try to leave by 2:48 PM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $12.96 one way or $25.92 round trip. Estimated CO2 is about 30.5 kg one way.
What should you check before leaving?
Before you leave, expect Partly Sunny around Killeen and Slight Chance Rain Showers near San Marcos.
Stop Ideas Near Round Rock
Useful break, food, and waypoint ideas within about 15 miles of the route midpoint.
Transit and Meeting Points
Useful pickup, handoff, or rendezvous points close to Round Rock.
Taylor
Austin
Killeen, Texas
Fort Hood, Texas
Flight Path Map
This map shows the direct air route between Killeen and San Marcos. Straight-line distance: 86.2 mi (138.72 km).
#1 Killeen
The 11th most populous city in Texas.
| Population | 153,991 |
| Coordinates | 31.1171200, -97.7278000 |
| Altitude | 252 |
| Country | United States |
#2 San Marcos
The most populous city in Hays County, Texas.
| Population | 66,350 |
| Coordinates | 29.8832700, -97.9413900 |
| Altitude | 188 |
| Country | United States |
End: San Marcos (-97.94139, 29.88327)
Estimated Travel Time
Distance: 156 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 03h 14m |
| 40 mph (64.37 km/h) | 02h 25m |
| 50 mph (80.47 km/h) | 01h 56m |
| 60 mph (96.56 km/h) | 01h 37m |
| 70 mph (112.65 km/h) | 01h 23m |
| 80 mph (129 km/h) | 01h 12m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.78 | $12.96 | $25.92 |
| Mid-grade | $4.25 | $14.58 | $29.17 |
| Premium | $4.59 | $15.75 | $31.49 |
| Diesel | $3.99 | $13.70 | $27.39 |
Assumes 8.3 L/100 km (about 28.3 MPG). CO2 is an estimate and varies by vehicle, fuel blend, traffic, and terrain.
Prices in Texas · Apr 19, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.