How far is Byrnes Mill, MO from Saint Peters, MO?
The driving distance from Byrnes Mill, MO to Saint Peters, MO is about 39.7 miles (63.9 km), with a travel time of about 00h 45m by car.
- The straight-line flight distance is about 25.2 miles (40.5 km).
- For a round trip, plan for roughly 01h 31m 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 45m.
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 St.
Route Weather Snapshot
Check the forecast at both ends before you head out.
Chance Showers And Thunderstorms then Partly Sunny
Driving Route Map
The map below follows the saved road route between Byrnes Mill and Saint Peters.
Turn-by-Turn Driving Directions
Step-by-step road directions between Byrnes Mill and Saint Peters.
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1
Start on Upper Byrnes Mill Road
1.4 mi · 3 min · Upper Byrnes Mill Road
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2
Merge right
1695 ft · 24 sec
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3
Take the exit left toward MO 30 East
36 m · 2 sec
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4
Merge slight right
11.6 mi · 16 min
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5
Take the exit left toward I 270 North
2202 ft · 35 sec
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6
Merge slight left
14.7 mi · 18 min
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7
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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8
Keep slight left to continue on I 70 West: Kansas City
645 ft · 11 sec
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9
Continue on I 70 West: Kansas City
1 km · 57 sec
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10
Merge slight left
10.5 mi · 13 min
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11
Arrive at your destination
0 m · 1 sec
Car Route Details
A richer read on the saved driving route between Byrnes Mill and Saint Peters.
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 North
Merge slight left
14.7 mi · 00h 18m
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.
Sunny leaving Byrnes Mill and Chance Showers And Thunderstorms then Partly Sunny near Saint Peters.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from Byrnes Mill to Saint Peters?
The road trip is about 39.7 miles (63.9 km) and usually takes 00h 45m 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?
Town and Country is a useful midpoint, sitting about 20.4 miles from Byrnes Mill and 19.3 miles from Saint Peters.
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 14.5 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 4:58 PM CDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $5.28 one way or $10.56 round trip. Estimated CO2 is about 12.4 kg one way.
What should you check before leaving?
Before you leave, expect Sunny around Byrnes Mill and Chance Showers And Thunderstorms then Partly Sunny near Saint Peters.
Stop Ideas Near Town and Country
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 Town and Country.
Kirkwood
Gateway Transportation Center
Alton
Washington
Flight Path Map
This map shows the direct air route between Byrnes Mill and Saint Peters. Straight-line distance: 25.16 mi (40.49 km).
#1 Byrnes Mill
City in Jefferson County, Missouri, United States
| Population | 3,015 |
| Coordinates | 38.4378300, -90.5817900 |
| Altitude | 143 |
| Country | United States |
#2 Saint Peters
The most populous city in St.
| Population | 58,043 |
| Coordinates | 38.8003300, -90.6265100 |
| Altitude | 134 |
| Country | United States |
End: I 70 West (-90.626511, 38.800311)
Estimated Travel Time
Distance: 64 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 01h 19m |
| 40 mph (64.37 km/h) | 00h 59m |
| 50 mph (80.47 km/h) | 00h 47m |
| 60 mph (96.56 km/h) | 00h 39m |
| 70 mph (112.65 km/h) | 00h 34m |
| 80 mph (129 km/h) | 00h 29m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.77 | $5.28 | $10.56 |
| Mid-grade | $4.25 | $5.95 | $11.91 |
| Premium | $4.65 | $6.52 | $13.03 |
| Diesel | $5.30 | $7.43 | $14.85 |
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 02, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.