Distance between cities › USA › Missouri › Dexter, MO › Distance from Dexter to O Fallon Book Hotels

Distance from Dexter, MO to O Fallon, MO

Distance

192 mi

Time

3 hours 38 mins

Gas Cost

$17 - $33

There are 144.97 miles from Dexter to O Fallon in northwest direction and 192 miles (308.99 kilometers) by car, following the I-55 route.

Dexter and O Fallon are 3 hours 38 mins far apart, if you drive non-stop .

This is the fastest route from Dexter, MO to O Fallon, MO. The halfway point is Saint Mary, MO.

Dexter, MO and O Fallon, MO are in the same time zone (CDT). Current time in both locations is 3:51 am.

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Lowest Price Rental Cars in Dexter, MO

Planning on renting a car to go from Dexter, MO to O Fallon, MO? Here there are some offers to rent a car in Dexter, MO

Small

From $14

Intermediate

From $18

Full-size

From $24

SUVs

From $28

Vans

From $40

Compare rental car prices in Dexter »

Gas Consumption and Emissions

A car with a fuel efficiency of MPG will need 7.71 gallons of gas to cover the route between Dexter, MO and O Fallon, MO.

The estimated cost of gas to go from Dexter to O Fallon is $23.82.

During the route, an average car will release 151.07 pounds of CO₂ to the atmosphere. The carbon footprint would be 0.79 pounds of CO₂ per mile.

Average USA gas price used for calculation is $3.09 per gallon of regular gas. Price last updated on March 12, 2026.
Read more about our CO₂ calculation.

Halfway Point Between Dexter, MO and O Fallon, MO

If you want to meet halfway between Dexter, MO and O Fallon, MO or just make a stop in the middle of your trip, the exact coordinates of the halfway point of this route are 37.797848 and -89.953270, or 37º 47' 52.2528" N, 89º 57' 11.772" W. This location is 96 miles away from Dexter, MO and O Fallon, MO and it would take approximately 1 hour 49 mins to reach the halfway point from both locations.

Closest City or Town to Halfway Point

The closest town to the halfway point is Saint Mary, MO, situated 103 miles from Dexter, MO and 96 miles from O Fallon, MO. It would take 1 hour 43 mins to go from Dexter to Saint Mary and 1 hour 38 mins to go from O Fallon to Saint Mary.