How far is Saint Clair, MO from O'Fallon, MO?
The driving distance from Saint Clair, MO to O'Fallon, MO is about 50.1 miles (80.7 km), with a travel time of about 01h 04m by car.
- The straight-line flight distance is about 35.5 miles (57.2 km).
- For a round trip, plan for roughly 02h 08m 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 04m.
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.
Township in Harrison County, Missouri, United States
Route Weather Snapshot
Check the forecast at both ends before you head out.
Mostly Sunny
Mostly Sunny
Driving Route Map
The map below follows the saved road route between Saint Clair and O'Fallon.
Turn-by-Turn Driving Directions
Step-by-step road directions between Saint Clair and O'Fallon.
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1
Start on South Main Street
1.2 mi · 3 min · South Main Street
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2
Take the ramp slight right toward I 44 East: Saint Louis
1554 ft · 39 sec
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3
Merge slight left
12.5 mi · 13 min
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4
Take the exit slight right toward I 44 Business, MO 100 East: Gray Summit
970 ft · 28 sec
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5
Turn left onto Manchester Road
13.4 mi · 19 min · Manchester Road
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6
Take the exit slight right toward MO 109
1108 ft · 31 sec
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7
Enter the roundabout and take exit 3 toward the route
68 m · 4 sec
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8
Exit the roundabout
157 m · 11 sec
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9
Enter the roundabout and take exit 1 toward the route
30 m · 2 sec
-
10
Exit the roundabout
2129 ft · 45 sec
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11
Enter the roundabout and take exit 2 toward the route
29 m · 2 sec
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12
Exit the roundabout
4.3 mi · 7 min
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13
Enter the roundabout and take exit 2 toward South Eatherton Road
29 m · 1 sec · South Eatherton Road
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14
Exit the roundabout onto South Eatherton Road
2.4 mi · 5 min · South Eatherton Road
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15
Continue on Olive Street Road
1.5 km · 2 min · Olive Street Road
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16
Take the ramp left toward Chesterfield Airport Road
1.1 km · 1 min · Chesterfield Airport Road
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17
Merge slight left onto Avenue of the Saints
3.1 mi · 4 min · Avenue of the Saints
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18
Take the exit slight right toward MO K: O'Fallon
100 m · 6 sec
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19
Merge slight right onto North Outer Road
1650 ft · 31 sec · North Outer Road
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20
Continue on North Outer Road
946 ft · 18 sec · North Outer Road
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21
Turn right
3.3 mi · 5 min
-
22
Continue straight
1.5 mi · 3 min
-
23
Continue straight
1.6 mi · 3 min
-
24
Continue on South Main Street
3115 ft · 2 min · South Main Street
-
25
Turn right
8 m · 2 sec
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26
Arrive at your destination
0 m · 1 sec
Car Route Details
A richer read on the saved driving route between Saint Clair 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.
Manchester Road
Turn left onto Manchester Road
13.4 mi · 00h 19m
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.
Mostly Sunny leaving Saint Clair and Mostly Sunny near O'Fallon.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from Saint Clair to O'Fallon?
The road trip is about 50.1 miles (80.7 km) and usually takes 01h 04m 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?
Fox Creek is a useful midpoint, sitting about 23.6 miles from Saint Clair and 26.5 miles from O'Fallon.
How much longer is the road route than the straight-line distance?
The direct path is about 35.5 miles (57.2 km), while the road route adds roughly 14.6 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 4:22 PM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $6.67 one way or $13.35 round trip. Estimated CO2 is about 15.7 kg one way.
What should you check before leaving?
Before you leave, expect Mostly Sunny around Saint Clair and Mostly Sunny near O'Fallon.
Stop Ideas Near Fox Creek
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 Fox Creek.
Kirkwood
Washington
Gateway Transportation Center
Alton
Flight Path Map
This map shows the direct air route between Saint Clair and O'Fallon. Straight-line distance: 35.55 mi (57.22 km).
#1 Saint Clair
City in Franklin County, Missouri, United States
| Population | 4,689 |
| Coordinates | 38.3453300, -90.9809700 |
| Altitude | 234 |
| 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: 81 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 01h 40m |
| 40 mph (64.37 km/h) | 01h 15m |
| 50 mph (80.47 km/h) | 01h 00m |
| 60 mph (96.56 km/h) | 00h 50m |
| 70 mph (112.65 km/h) | 00h 42m |
| 80 mph (129 km/h) | 00h 37m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $6.67 | $13.35 |
| Mid-grade | $4.25 | $7.53 | $15.06 |
| Premium | $4.65 | $8.24 | $16.48 |
| Diesel | $5.30 | $9.39 | $18.78 |
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 23, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.