Distance between cities › USA › Idaho › Downey, ID › Distance from Downey to Roundup Book Hotels

Distance from Downey, ID to Roundup, MT

Distance

479 mi

Time

8 hours 51 mins

Gas Cost

$45 - $87

There are 328.93 miles from Downey to Roundup in northeast direction and 479 miles (770.88 kilometers) by car, following the I-90 and US-191 route.

Downey and Roundup are 8 hours 51 mins far apart, if you drive non-stop .

This is the fastest route from Downey, ID to Roundup, MT. The halfway point is Big Sky, MT.

Downey, ID and Roundup, MT are in the same time zone (MDT). Current time in both locations is 11:36 pm.

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Lowest Price Rental Cars in Downey, ID

Planning on renting a car to go from Downey, ID to Roundup, MT? Here there are some offers to rent a car in Downey, ID

Small

From $14

Intermediate

From $18

Full-size

From $24

SUVs

From $28

Vans

From $40

Compare rental car prices in Downey »

Gas Consumption and Emissions

A car with a fuel efficiency of MPG will need 19.24 gallons of gas to cover the route between Downey, ID and Roundup, MT.

The estimated cost of gas to go from Downey to Roundup is $62.76.

During the route, an average car will release 376.93 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 $3.26 per gallon of regular gas. Price last updated on March 12, 2026.
Read more about our CO₂ calculation.

Halfway Point Between Downey, ID and Roundup, MT

If you want to meet halfway between Downey, ID and Roundup, MT or just make a stop in the middle of your trip, the exact coordinates of the halfway point of this route are 45.367714 and -111.177162, or 45º 22' 3.7704" N, 111º 10' 37.7832" W. This location is 239.52 miles away from Downey, ID and Roundup, MT and it would take approximately 4 hours 25 mins to reach the halfway point from both locations.

Closest City or Town to Halfway Point

The closest town to the halfway point is Big Sky, MT, situated 247 miles from Downey, ID and 237 miles from Roundup, MT. It would take 4 hours 22 mins to go from Downey to Big Sky and 4 hours 19 mins to go from Roundup to Big Sky.