How far is St. Louis, MO from O'Fallon, MO?
The driving distance from St. Louis, MO to O'Fallon, MO is about 34.1 miles (54.8 km), with a travel time of about 00h 38m by car.
- The straight-line flight distance is about 29.9 miles (48.1 km).
- For a round trip, plan for roughly 01h 16m of driving time before adding stops, traffic, or weather delays.
- A comfortable departure window is usually 7:00 AM to 7:00 PM CDT.
Reverse, save, or send this route
This is an easy same-day return drive. Copy the route link, send it to another device, or print a clean version before you head out.
This is an easy same-day return drive.
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 00h 38m.
This is a short drive, so your comfort window is wide. Traffic and current weather matter more than the clock.
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.
Route Weather Snapshot
Check the forecast at both ends before you head out.
Showers And Thunderstorms Likely
Showers And Thunderstorms
Driving Route Map
The map below follows the saved road route between St. Louis and O'Fallon.
Turn-by-Turn Driving Directions
Step-by-step road directions between St. Louis and O'Fallon.
-
1
Start on Market Street
26 m · 6 sec · Market Street
-
2
Turn right onto North Tucker Boulevard
1.3 km · 2 min · North Tucker Boulevard
-
3
Turn left onto North 13th Street
1274 ft · 25 sec · North 13th Street
-
4
Continue on North 13th Street
111 m · 6 sec · North 13th Street
-
5
Continue on North Florissant Avenue
3.5 mi · 6 min · North Florissant Avenue
-
6
Take the ramp slight left toward I 70 West
773 ft · 12 sec
-
7
Merge slight left onto Mark Twain Expressway
26.7 mi · 34 min · Mark Twain Expressway
-
8
Take the exit slight right toward MO K: O'Fallon, Main Street
119 m · 8 sec
-
9
Turn straight onto East Terra Lane
1.4 km · 2 min · East Terra Lane
-
10
Turn right onto South Main Street
2830 ft · 1 min · South Main Street
-
11
Turn right
8 m · 2 sec
-
12
Arrive at your destination
0 m · 1 sec
Car Route Details
A richer read on the saved driving route between St. Louis and O'Fallon.
Turn-heavy local drive
The route has frequent decision points for its length, so lane choice and turn timing will matter more than cruising speed.
Mark Twain Expressway
Merge slight left onto Mark Twain Expressway
26.7 mi · 00h 34m
Route Summary
A quick read on whether this route feels easy, ambitious, or worth planning around.
A short regional drive
This route is short enough to handle as a quick errand, commute, or easy same-day return without much planning overhead.
Showers And Thunderstorms Likely leaving St. Louis and Showers And Thunderstorms near O'Fallon.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from St. Louis to O'Fallon?
The road trip is about 34.1 miles (54.8 km) and usually takes 00h 38m in normal driving conditions.
Is this a same-day trip or an overnight route?
This route is short enough to handle as a quick errand, commute, or easy same-day return without much planning overhead.
What is the halfway point on this route?
Bridgeton is a useful midpoint, sitting about 16.5 miles from St. Louis and 17.6 miles from O'Fallon.
How much longer is the road route than the straight-line distance?
The direct path is about 29.9 miles (48.1 km), while the road route adds roughly 4.2 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 7:00 AM to 7:00 PM CDT. If you want a more comfortable same-day return, try to leave by 7:14 PM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $4.53 one way or $9.05 round trip. Estimated CO2 is about 10.7 kg one way.
What should you check before leaving?
Before you leave, expect Showers And Thunderstorms Likely around St. Louis and Showers And Thunderstorms near O'Fallon.
Stop Ideas Near Bridgeton
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 Bridgeton.
Kirkwood
Gateway Transportation Center
Alton
Washington
Flight Path Map
This map shows the direct air route between St. Louis and O'Fallon. Straight-line distance: 29.88 mi (48.08 km).
#1 St. Louis
The second most populous city in Missouri and the center of the St.
| Population | 315,685 |
| Coordinates | 38.6272700, -90.1978900 |
| Altitude | 142 |
| Country | United States |
#2 O'Fallon
The most populous city in St.
| Population | 89,769 |
| Coordinates | 38.8106100, -90.6998500 |
| Altitude | 165 |
| Country | United States |
End: (-90.699849, 38.810674)
Estimated Travel Time
Distance: 55 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 01h 08m |
| 40 mph (64.37 km/h) | 00h 51m |
| 50 mph (80.47 km/h) | 00h 40m |
| 60 mph (96.56 km/h) | 00h 34m |
| 70 mph (112.65 km/h) | 00h 29m |
| 80 mph (129 km/h) | 00h 25m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $4.53 | $9.05 |
| Mid-grade | $4.25 | $5.10 | $10.21 |
| Premium | $4.65 | $5.58 | $11.17 |
| Diesel | $5.30 | $6.36 | $12.73 |
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 Missouri · Apr 24, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.