How far is Lamar, MO from O'Fallon, MO?
The driving distance from Lamar, MO to O'Fallon, MO is about 279.3 miles (449.5 km), with a travel time of about 04h 33m by car.
- The straight-line flight distance is about 214.5 miles (345.2 km).
- For a round trip, plan for roughly 09h 07m of driving time before adding stops, traffic, or weather delays.
- A comfortable departure window is usually 6:00 AM to 8:00 AM CDT.
Reverse, save, or send this route
This drive is better planned with a longer stop or an overnight stay. Copy the route link, send it to another device, or print a clean version before you head out.
This drive is better planned with a longer stop or an overnight stay.
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 04h 33m.
An early departure helps you fit a real stop into the day without turning the return into a late-night drive.
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.
Human settlement in Missouri, United States of America
Route Weather Snapshot
Check the forecast at both ends before you head out.
Slight Chance Rain Showers then Mostly Sunny
Driving Route Map
The map below follows the saved road route between Lamar and O'Fallon.
Turn-by-Turn Driving Directions
Step-by-step road directions between Lamar and O'Fallon.
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1
Start on the route
41 m · 12 sec
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2
Turn right onto 11th Street West
77 m · 7 sec · 11th Street West
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3
Turn left onto Gulf Street
144 m · 29 sec · Gulf Street
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4
Turn right onto 12th Street West
1.3 mi · 2 min · 12th Street West
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5
Take the ramp left toward I 49 South, US 71 South: Joplin
947 ft · 12 sec
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6
Merge slight left
19.6 mi · 21 min
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7
Take the exit slight right toward MO V, MO D: Alba
1611 ft · 30 sec
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8
Turn left onto North Garrison Avenue
1.6 km · 2 min · North Garrison Avenue
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9
Turn left onto East Northwoods Street
1212 ft · 23 sec · East Northwoods Street
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10
Continue on East Java Street
1.3 km · 1 min · East Java Street
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11
Turn left
36 mi · 42 min
-
12
Take the ramp straight toward I 44 East: Springfield
3171 ft · 1 min
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13
Merge slight left
194.8 mi · 3 hr 31 min
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14
Take the exit slight right toward I 44 Business, MO 100 East: Gray Summit
970 ft · 28 sec
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15
Turn left onto Manchester Road
13.4 mi · 19 min · Manchester Road
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16
Take the exit slight right toward MO 109
1108 ft · 31 sec
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17
Enter the roundabout and take exit 3 toward the route
68 m · 4 sec
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18
Exit the roundabout
157 m · 11 sec
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19
Enter the roundabout and take exit 1 toward the route
30 m · 2 sec
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20
Exit the roundabout
2129 ft · 45 sec
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21
Enter the roundabout and take exit 2 toward the route
29 m · 2 sec
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22
Exit the roundabout
4.3 mi · 7 min
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23
Enter the roundabout and take exit 2 toward South Eatherton Road
29 m · 1 sec · South Eatherton Road
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24
Exit the roundabout onto South Eatherton Road
2.4 mi · 5 min · South Eatherton Road
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25
Continue on Olive Street Road
1.5 km · 2 min · Olive Street Road
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26
Take the ramp left toward Chesterfield Airport Road
1.1 km · 1 min · Chesterfield Airport Road
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27
Merge slight left onto Avenue of the Saints
3.1 mi · 4 min · Avenue of the Saints
-
28
Take the exit slight right toward MO K: O'Fallon
100 m · 6 sec
-
29
Merge slight right onto North Outer Road
1650 ft · 31 sec · North Outer Road
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30
Continue on North Outer Road
946 ft · 18 sec · North Outer Road
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31
Turn right
3.3 mi · 5 min
-
32
Continue straight
1.5 mi · 3 min
-
33
Continue straight
1.6 mi · 3 min
-
34
Continue on South Main Street
3115 ft · 2 min · South Main Street
-
35
Turn right
8 m · 2 sec
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36
Arrive at your destination
0 m · 1 sec
Car Route Details
A richer read on the saved driving route between Lamar 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 44 East
Merge slight left
195 mi · 03h 31m
Route Summary
A quick read on whether this route feels easy, ambitious, or worth planning around.
A longer out-and-back drive
This is still possible in one day, but it becomes a long driving day. Leaving early and planning your stop window matters more here.
Partly Sunny leaving Lamar and Slight Chance Rain Showers then 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 Lamar to O'Fallon?
The road trip is about 279.3 miles (449.5 km) and usually takes 04h 33m in normal driving conditions.
Is this a same-day trip or an overnight route?
This is still possible in one day, but it becomes a long driving day. Leaving early and planning your stop window matters more here.
What is the halfway point on this route?
Stoutland is a useful midpoint, sitting about 144 miles from Lamar and 135.3 miles from O'Fallon.
How much longer is the road route than the straight-line distance?
The direct path is about 214.5 miles (345.2 km), while the road route adds roughly 64.8 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 6:00 AM to 8:00 AM CDT. If you want a more comfortable same-day return, try to leave by 7:52 AM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $37.18 one way or $74.36 round trip. Estimated CO2 is about 87.6 kg one way.
What should you check before leaving?
Before you leave, expect Partly Sunny around Lamar and Slight Chance Rain Showers then Mostly Sunny near O'Fallon.
Stop Ideas Near Stoutland
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 Stoutland.
Jefferson City
Sedalia
Flight Path Map
This map shows the direct air route between Lamar and O'Fallon. Straight-line distance: 214.52 mi (345.24 km).
#1 Lamar
City in Missouri
| Population | 4,233 |
| Coordinates | 37.4950500, -94.2766100 |
| Altitude | 293 |
| 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: 450 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 09h 18m |
| 40 mph (64.37 km/h) | 06h 59m |
| 50 mph (80.47 km/h) | 05h 35m |
| 60 mph (96.56 km/h) | 04h 39m |
| 70 mph (112.65 km/h) | 03h 59m |
| 80 mph (129 km/h) | 03h 29m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $37.18 | $74.36 |
| Mid-grade | $4.25 | $41.93 | $83.87 |
| Premium | $4.65 | $45.89 | $91.78 |
| Diesel | $5.30 | $52.30 | $104.59 |
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 · May 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.