How far is O'Fallon, MO from Byrnes Mill, MO?
The driving distance from O'Fallon, MO to Byrnes Mill, MO is about 38.2 miles (61.4 km), with a travel time of about 00h 59m by car.
- The straight-line flight distance is about 26.5 miles (42.7 km).
- For a round trip, plan for roughly 01h 58m 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 00h 59m.
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 Missouri, United States
Route Weather Snapshot
Check the forecast at both ends before you head out.
Chance Showers And Thunderstorms
Mostly Cloudy then Chance Rain Showers
Driving Route Map
The map below follows the saved road route between O'Fallon and Byrnes Mill.
Turn-by-Turn Driving Directions
Step-by-step road directions between O'Fallon and Byrnes Mill.
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1
Start on the route
8 m · 7 sec
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2
Turn left onto South Main Street
2865 ft · 1 min · South Main Street
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3
Continue straight
3.1 mi · 6 min
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4
Continue straight
3.4 mi · 5 min
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5
Take the ramp slight right toward I 64 East, US 40 East, US 61 South
1523 ft · 22 sec
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6
Merge slight left onto Avenue of the Saints
12.3 mi · 15 min · Avenue of the Saints
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7
Take the exit slight right toward MO 141
1368 ft · 34 sec
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8
Turn right onto MO 141: Manchester
56 m · 6 sec
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9
Merge slight left
8.5 mi · 13 min
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10
Turn right onto Hawkins Road
1.6 mi · 4 min · Hawkins Road
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11
Continue on New Sugar Creek Road
1 mi · 2 min · New Sugar Creek Road
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12
Take the ramp slight right toward MO 30 West
56 m · 3 sec
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13
Merge slight left
5.6 mi · 7 min
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14
Take the exit slight right toward Upper Byrnes Mill Road
33 m · 3 sec
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15
Turn slight right onto Upper Byrnes Mill Road
1.4 mi · 4 min · Upper Byrnes Mill Road
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16
Arrive at your destination
0 m · 1 sec · Upper Byrnes Mill Road
Car Route Details
A richer read on the saved driving route between O'Fallon and Byrnes Mill.
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.
Avenue of the Saints
Merge slight left onto Avenue of the Saints
12.3 mi · 00h 15m
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.
Chance Showers And Thunderstorms leaving O'Fallon and Mostly Cloudy then Chance Rain Showers near Byrnes Mill.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from O'Fallon to Byrnes Mill?
The road trip is about 38.2 miles (61.4 km) and usually takes 00h 59m 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?
Lake is a useful midpoint, sitting about 19.1 miles from O'Fallon and 19.1 miles from Byrnes Mill.
How much longer is the road route than the straight-line distance?
The direct path is about 26.5 miles (42.7 km), while the road route adds roughly 11.7 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 4:32 PM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $5.05 one way or $10.11 round trip. Estimated CO2 is about 11.9 kg one way.
What should you check before leaving?
Before you leave, expect Chance Showers And Thunderstorms around O'Fallon and Mostly Cloudy then Chance Rain Showers near Byrnes Mill.
Stop Ideas Near Lake
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 Lake.
Kirkwood
Gateway Transportation Center
Alton
Washington
Flight Path Map
This map shows the direct air route between O'Fallon and Byrnes Mill. Straight-line distance: 26.53 mi (42.7 km).
#1 O'Fallon
The most populous city in St.
| Population | 89,769 |
| Coordinates | 38.8106100, -90.6998500 |
| Altitude | 165 |
| Country | United States |
#2 Byrnes Mill
City in Jefferson County, Missouri, United States
| Population | 3,015 |
| Coordinates | 38.4378300, -90.5817900 |
| Altitude | 143 |
| Country | United States |
End: Byrnes Mill (-90.58179, 38.43783)
Estimated Travel Time
Distance: 61 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 01h 16m |
| 40 mph (64.37 km/h) | 00h 57m |
| 50 mph (80.47 km/h) | 00h 45m |
| 60 mph (96.56 km/h) | 00h 38m |
| 70 mph (112.65 km/h) | 00h 32m |
| 80 mph (129 km/h) | 00h 28m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $5.05 | $10.11 |
| Mid-grade | $4.25 | $5.70 | $11.40 |
| Premium | $4.65 | $6.24 | $12.47 |
| Diesel | $5.30 | $7.11 | $14.21 |
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 12, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.