How far is Frontenac, MO from O'Fallon, MO?
The driving distance from Frontenac, MO to O'Fallon, MO is about 25 miles (40.2 km), with a travel time of about 00h 26m by car.
- The straight-line flight distance is about 19.5 miles (31.4 km).
- For a round trip, plan for roughly 00h 52m 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 26m.
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.
A city in St.
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 Frontenac and O'Fallon.
Turn-by-Turn Driving Directions
Step-by-step road directions between Frontenac and O'Fallon.
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1
Start on Avenue of the Saints
1.6 mi · 2 min · Avenue of the Saints
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2
Take the exit slight right toward I 270: Memphis, Chicago
781 ft · 17 sec
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3
Keep slight right to continue on I 270 North: Chicago
1373 ft · 26 sec
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4
Merge slight left
6.1 mi · 8 min
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5
Take the exit slight right toward I 70: Kansas City, Saint Louis, Saint Louis Lambert International Airport
1 mi · 1 min
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6
Keep slight left to continue on I 70 West: Kansas City
645 ft · 11 sec
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7
Continue on I 70 West: Kansas City
1 km · 57 sec
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8
Merge slight left
13.6 mi · 17 min
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9
Take the exit slight right toward MO K: O'Fallon, Main Street
119 m · 8 sec
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10
Turn straight onto East Terra Lane
1.4 km · 2 min · East Terra Lane
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11
Turn right onto South Main Street
2830 ft · 1 min · South Main Street
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12
Turn right
8 m · 2 sec
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13
Arrive at your destination
0 m · 1 sec
Car Route Details
A richer read on the saved driving route between Frontenac 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.
I 70 West
Merge slight left
13.6 mi · 00h 17m
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.
Mostly Sunny leaving Frontenac 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 Frontenac to O'Fallon?
The road trip is about 25 miles (40.2 km) and usually takes 00h 26m 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?
Saint Charles is a useful midpoint, sitting about 12.5 miles from Frontenac and 12.5 miles from O'Fallon.
How much longer is the road route than the straight-line distance?
The direct path is about 19.5 miles (31.4 km), while the road route adds roughly 5.5 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 7:38 PM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $3.32 one way or $6.64 round trip. Estimated CO2 is about 7.8 kg one way.
What should you check before leaving?
Before you leave, expect Mostly Sunny around Frontenac and Mostly Sunny near O'Fallon.
Stop Ideas Near Saint Charles
Useful break, food, and waypoint ideas within about 15 miles of the route midpoint.
City Hall Park
Jennings City Hall
Ferguson Finance Director
Transit and Meeting Points
Useful pickup, handoff, or rendezvous points close to Saint Charles.
Kirkwood
Gateway Transportation Center
Alton
Washington
Flight Path Map
This map shows the direct air route between Frontenac and O'Fallon. Straight-line distance: 19.54 mi (31.44 km).
#1 Frontenac
City in Missouri, USA
| Population | 3,599 |
| Coordinates | 38.6356100, -90.4151200 |
| Altitude | 176 |
| 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: 40 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 00h 49m |
| 40 mph (64.37 km/h) | 00h 37m |
| 50 mph (80.47 km/h) | 00h 29m |
| 60 mph (96.56 km/h) | 00h 24m |
| 70 mph (112.65 km/h) | 00h 21m |
| 80 mph (129 km/h) | 00h 18m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $3.32 | $6.64 |
| Mid-grade | $4.25 | $3.74 | $7.49 |
| Premium | $4.65 | $4.10 | $8.19 |
| Diesel | $5.30 | $4.67 | $9.34 |
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.