How far is Saint Peters, MO from Byrnes Mill, MO?
The driving distance from Saint Peters, MO to Byrnes Mill, MO is about 42.8 miles (68.9 km), with a travel time of about 00h 56m by car.
- The straight-line flight distance is about 25.2 miles (40.5 km).
- For a round trip, plan for roughly 01h 53m 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 56m.
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.
Village in west St.
Route Weather Snapshot
Check the forecast at both ends before you head out.
Chance Rain Showers
Chance Showers And Thunderstorms
Driving Route Map
The map below follows the saved road route between Saint Peters and Byrnes Mill.
Turn-by-Turn Driving Directions
Step-by-step road directions between Saint Peters and Byrnes Mill.
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1
Start on the route
1.2 mi · 1 min
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2
Take the exit slight right toward MO 79: Elsberry, Louisiana
725 ft · 15 sec
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3
Keep slight left to continue on MO 79
117 m · 15 sec
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4
Turn left
652 ft · 11 sec
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5
Take the ramp slight right toward I 70 East
1294 ft · 19 sec
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6
Merge slight left
11.9 mi · 15 min
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7
Take the exit slight right toward I 270: Chicago, Memphis
872 ft · 12 sec
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8
Keep slight right to continue on I 270 South: Memphis
2339 ft · 33 sec
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9
Continue on I 270 South: Memphis
723 ft · 10 sec
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10
Merge slight left
15.6 mi · 19 min
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11
Take the exit slight right toward MO 30: Gravois Road
1580 ft · 34 sec
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12
Keep slight right to continue on MO 30 West: Fenton
93 m · 8 sec
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13
Merge slight left
11.1 mi · 15 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 Saint Peters and Byrnes Mill.
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 270 South
Merge slight left
15.6 mi · 00h 19m
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 Rain Showers leaving Saint Peters and Chance Showers And Thunderstorms near Byrnes Mill.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from Saint Peters to Byrnes Mill?
The road trip is about 42.8 miles (68.9 km) and usually takes 00h 56m 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?
Westwood is a useful midpoint, sitting about 21.4 miles from Saint Peters and 21.4 miles from Byrnes Mill.
How much longer is the road route than the straight-line distance?
The direct path is about 25.2 miles (40.5 km), while the road route adds roughly 17.6 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 4:36 PM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $5.69 one way or $11.39 round trip. Estimated CO2 is about 13.4 kg one way.
What should you check before leaving?
Before you leave, expect Chance Rain Showers around Saint Peters and Chance Showers And Thunderstorms near Byrnes Mill.
Stop Ideas Near Westwood
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 Westwood.
Kirkwood
Gateway Transportation Center
Alton
Washington
Flight Path Map
This map shows the direct air route between Saint Peters and Byrnes Mill. Straight-line distance: 25.16 mi (40.49 km).
#1 Saint Peters
The most populous city in St.
| Population | 58,043 |
| Coordinates | 38.8003300, -90.6265100 |
| Altitude | 134 |
| 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: 69 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 01h 25m |
| 40 mph (64.37 km/h) | 01h 04m |
| 50 mph (80.47 km/h) | 00h 51m |
| 60 mph (96.56 km/h) | 00h 42m |
| 70 mph (112.65 km/h) | 00h 36m |
| 80 mph (129 km/h) | 00h 32m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $5.69 | $11.39 |
| Mid-grade | $4.25 | $6.42 | $12.84 |
| Premium | $4.65 | $7.03 | $14.06 |
| Diesel | $5.30 | $8.01 | $16.02 |
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.