How far is Castor, MO from O'Fallon, MO?
The driving distance from Castor, MO to O'Fallon, MO is about 168.6 miles (271.3 km), with a travel time of about 02h 46m by car.
- The straight-line flight distance is about 126.7 miles (203.9 km).
- For a round trip, plan for roughly 05h 32m 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 02h 46m.
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.
City in and the county seat of Ste.
Route Weather Snapshot
Check the forecast at both ends before you head out.
Showers And Thunderstorms Likely then Chance Showers And Thunderstorms
Showers And Thunderstorms Likely then Chance Showers And Thunderstorms
Driving Route Map
The map below follows the saved road route between Castor and O'Fallon.
Turn-by-Turn Driving Directions
Step-by-step road directions between Castor and O'Fallon.
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1
Start on County Road 640
1.7 mi · 7 min · County Road 640
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2
At the end of the road, turn left
1.5 mi · 3 min
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3
At the end of the road, turn right
2.7 mi · 5 min
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4
Continue straight
1753 ft · 34 sec
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5
At the end of the road, turn left
15.8 mi · 24 min
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6
Enter the roundabout and take exit 2 toward Interstate 55
60 m · 4 sec
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7
Exit the roundabout onto Interstate 55
5.7 mi · 8 min
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8
Take the ramp left toward I 55 North, US 61 North: Cape Girardeau
1122 ft · 28 sec
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9
Merge slight left
1.4 mi · 1 min
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10
Keep slight left
101.5 mi · 1 hr 49 min
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11
Continue on Rosa Parks Highway
1.3 mi · 2 min · Rosa Parks Highway
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12
Take the exit slight right toward I 270 West, I 255 East: Kansas City, Chicago
1279 ft · 27 sec
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13
Keep slight left to continue on I 270 West: Kansas City
118 m · 8 sec
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14
Continue on I 270 West
1.2 km · 1 min
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15
Merge slight left
18.1 mi · 23 min
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16
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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17
Keep slight left to continue on I 70 West: Kansas City
645 ft · 11 sec
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18
Continue on I 70 West: Kansas City
1 km · 57 sec
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19
Merge slight left
13.6 mi · 17 min
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20
Take the exit slight right toward MO K: O'Fallon, Main Street
119 m · 8 sec
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21
Turn straight onto East Terra Lane
1.4 km · 2 min · East Terra Lane
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22
Turn right onto South Main Street
2830 ft · 1 min · South Main Street
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23
Turn right
8 m · 2 sec
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24
Arrive at your destination
0 m · 1 sec
Car Route Details
A richer read on the saved driving route between Castor and O'Fallon.
Highway-focused drive
Most of the mileage stays on named highways, so the important moments are ramps, exits, merges, and the final local approach.
I 55 North
Keep slight left
102 mi · 01h 49m
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.
Showers And Thunderstorms Likely then Chance Showers And Thunderstorms leaving Castor and Showers And Thunderstorms Likely then Chance 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 Castor to O'Fallon?
The road trip is about 168.6 miles (271.3 km) and usually takes 02h 46m 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?
Sainte Genevieve is a useful midpoint, sitting about 84.2 miles from Castor and 84.4 miles from O'Fallon.
How much longer is the road route than the straight-line distance?
The direct path is about 126.7 miles (203.9 km), while the road route adds roughly 41.9 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 12:58 PM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $22.44 one way or $44.87 round trip. Estimated CO2 is about 52.9 kg one way.
What should you check before leaving?
Before you leave, expect Showers And Thunderstorms Likely then Chance Showers And Thunderstorms around Castor and Showers And Thunderstorms Likely then Chance Showers And Thunderstorms near O'Fallon.
Stop Ideas Near Sainte Genevieve
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 Sainte Genevieve.
Du Quoin
Gateway Transportation Center
Kirkwood
Carbondale station
Flight Path Map
This map shows the direct air route between Castor and O'Fallon. Straight-line distance: 126.68 mi (203.87 km).
#1 Castor
Unincorporated community in Missouri
| Population | 4,951 |
| Coordinates | 37.0675500, -89.9787100 |
| Altitude | 107 |
| 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: 271 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 05h 36m |
| 40 mph (64.37 km/h) | 04h 12m |
| 50 mph (80.47 km/h) | 03h 22m |
| 60 mph (96.56 km/h) | 02h 48m |
| 70 mph (112.65 km/h) | 02h 24m |
| 80 mph (129 km/h) | 02h 06m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $22.44 | $44.87 |
| Mid-grade | $4.25 | $25.31 | $50.61 |
| Premium | $4.65 | $27.69 | $55.38 |
| Diesel | $5.30 | $31.56 | $63.12 |
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 · Jun 01, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.