How far is Thayer, MO from O'Fallon, MO?
The driving distance from Thayer, MO to O'Fallon, MO is about 225.8 miles (363.4 km), with a travel time of about 03h 57m by car.
- The straight-line flight distance is about 164.5 miles (264.7 km).
- For a round trip, plan for roughly 07h 54m 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 03h 57m.
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.
City in Phelps County, Missouri, United States
Route Weather Snapshot
Check the forecast at both ends before you head out.
Chance Showers And Thunderstorms then Showers And Thunderstorms
Showers And Thunderstorms
Driving Route Map
The map below follows the saved road route between Thayer and O'Fallon.
Turn-by-Turn Driving Directions
Step-by-step road directions between Thayer and O'Fallon.
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1
Start on the route
23 m · 11 sec
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2
Turn sharp left onto Front Street
133 m · 18 sec · Front Street
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3
Turn left onto Walnut Street
911 ft · 27 sec · Walnut Street
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4
Turn left
57.6 mi · 1 hr 11 min
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5
Take the exit slight right toward US 63 North, US 60 Business: Houston, Rolla
65.8 mi · 1 hr 23 min
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6
Continue on North Bishop Avenue
87 m · 5 sec · North Bishop Avenue
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7
Keep slight left to continue on North Bishop Avenue
56 m · 3 sec · North Bishop Avenue
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8
Keep slight right to continue on Tim Bradley Way
1336 ft · 33 sec · Tim Bradley Way
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9
Take the ramp right toward I 44 East: Saint Louis
564 ft · 14 sec
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10
Merge slight left
67.3 mi · 1 hr 12 min
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11
Take the exit slight right toward I 44 Business, MO 100 East: Gray Summit
970 ft · 28 sec
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12
Turn left onto Manchester Road
13.4 mi · 19 min · Manchester Road
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13
Take the exit slight right toward MO 109
1108 ft · 31 sec
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14
Enter the roundabout and take exit 3 toward the route
68 m · 4 sec
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15
Exit the roundabout
157 m · 11 sec
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16
Enter the roundabout and take exit 1 toward the route
30 m · 2 sec
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17
Exit the roundabout
2129 ft · 45 sec
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18
Enter the roundabout and take exit 2 toward the route
29 m · 2 sec
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19
Exit the roundabout
4.3 mi · 7 min
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20
Enter the roundabout and take exit 2 toward South Eatherton Road
29 m · 1 sec · South Eatherton Road
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21
Exit the roundabout onto South Eatherton Road
2.4 mi · 5 min · South Eatherton Road
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22
Continue on Olive Street Road
1.5 km · 2 min · Olive Street Road
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23
Take the ramp left toward Chesterfield Airport Road
1.1 km · 1 min · Chesterfield Airport Road
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24
Merge slight left onto Avenue of the Saints
3.1 mi · 4 min · Avenue of the Saints
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25
Take the exit slight right toward MO K: O'Fallon
100 m · 6 sec
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26
Merge slight right onto North Outer Road
1650 ft · 31 sec · North Outer Road
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27
Continue on North Outer Road
946 ft · 18 sec · North Outer Road
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28
Turn right
3.3 mi · 5 min
-
29
Continue straight
1.5 mi · 3 min
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30
Continue straight
1.6 mi · 3 min
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31
Continue on South Main Street
3115 ft · 2 min · South Main Street
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32
Turn right
8 m · 2 sec
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33
Arrive at your destination
0 m · 1 sec
Car Route Details
A richer read on the saved driving route between Thayer 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
67.3 mi · 01h 12m
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.
Chance Showers And Thunderstorms then Showers And Thunderstorms leaving Thayer 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 Thayer to O'Fallon?
The road trip is about 225.8 miles (363.4 km) and usually takes 03h 57m 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?
Edgar Springs is a useful midpoint, sitting about 112.4 miles from Thayer and 113.4 miles from O'Fallon.
How much longer is the road route than the straight-line distance?
The direct path is about 164.5 miles (264.7 km), while the road route adds roughly 61.3 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 9:06 AM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $30.05 one way or $60.11 round trip. Estimated CO2 is about 70.8 kg one way.
What should you check before leaving?
Before you leave, expect Chance Showers And Thunderstorms then Showers And Thunderstorms around Thayer and Showers And Thunderstorms near O'Fallon.
Stop Ideas Near Edgar Springs
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 Edgar Springs.
Jefferson City
Hermann
Flight Path Map
This map shows the direct air route between Thayer and O'Fallon. Straight-line distance: 164.47 mi (264.69 km).
#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: 363 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 07h 31m |
| 40 mph (64.37 km/h) | 05h 38m |
| 50 mph (80.47 km/h) | 04h 30m |
| 60 mph (96.56 km/h) | 03h 45m |
| 70 mph (112.65 km/h) | 03h 13m |
| 80 mph (129 km/h) | 02h 49m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $30.05 | $60.11 |
| Mid-grade | $4.25 | $33.90 | $67.79 |
| Premium | $4.65 | $37.09 | $74.18 |
| Diesel | $5.30 | $42.27 | $84.55 |
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 05, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.