The cheapest times to fly from STL to BOI are

  • January 8th to February 25th (except the week of February 12th)
  • April 23rd to May 6th
  • May 28th to June 10th
  • August 6th to November 18th

based on data collected exclusively by Champion Traveler across tens of millions of flights. Among all the dates above, the very cheapest time to fly from STL to BOI is mid October. Prices can be as high as $941 for Sunday flights during early to mid March, or as low as $279 for Tuesday flights around mid October.


When to Fly to Boise

Flying from St. Louis, MO (STL) to Boise, ID (BOI) will usually cost between $280 to $529 per person if booking more than four weeks in advance. On average the very cheapest time to fly is mid October with an average ticket price of $317. Due to high demand the most expensive time to fly is early to mid March, with an average price of $499. Planning your trip to low-cost times can easily save you $182 on economy flights and even more on first-class flights. Generally, any price below $402 can be considered a good price for a round-trip STL to BOI flight.

See below for a graph of average weekly prices for the STL to BOI route. All prices are for round-trip tickets in USD.

STL to BOI Flight Prices

Compared to other flights, the STL to BOI flight is much cheaper than the average and costs much less than the average flight leaving from St. Louis. The average price per mile (for a direct flight) is $0.18, which is below average.


Flight Prices by Day of the Week

Tuesday is usually the cheapest day to depart and return on this flight. Sundays are the most expensive days to fly out or take a return trip. Selecting flights on the least expensive days could save you up to $126 (27%) on this flight.

Departing prices are for round-trip flights returning on the day of departure. For example, a flight departing on Tuesday and returning a week later will cost an average of $332. Return trip prices are from the BOI to STL flight, and often highlight the quality of our data in showing the same trend.

Departing Prices by Day

Departure Day Prices

Return Trip Prices by Day

Return Day Prices


Nonstop Flights and Layovers

Travelers looking to fly from STL to BOI can generally find a 1-layover flight. Because there is not usually a direct flight option the real-world direct flight time of 3 hour 28 minutes may not be realistic.


Alternative Nearby Airports

Champion Traveler tells you which airports are nearby and whether tickets might be cheaper alternative airports nearby. Sometimes it’s worth it to fly into a closer airport and then commute to your destination. Remember that there is not usually a nonstop flight from STL to BOI while comparing.

Destination alternative #1: Joslin Field – Magic Valley Regional Airport (TWF) in Twin Falls, ID

  • 115 miles (185 km) away from BOI
  • Usually 7.96% less expensive than BOI
  • 1-layover flights available

See STL to TWF flights


Flight Questions Answered

Still have questions about flying from STL to BOI? We’ve got answers.

Which airlines fly this route?

You can find 6 major airlines flying this route most often: Alaska, American, Delta, Frontier, Southwest, United, and potentially more during busy seasons.

How far away is it from Boise Air Terminal Airport to St Louis Lambert International Airport?

The distance between the two airports is roughly 1379 miles or 2219 kilometers.

How long does it take to fly from STL to BOI?

The real-world flight time for a nonstop STL to BOI flight is about 3 hour 28 minutes.

How many flights go between St. Louis, MO and Boise, ID?

It depends on the day of the week and the date, but a typical day might have around 72 available flights from STL to BOI.


Airport Location Info


Departing Airport

Origination codeSTL
Origination airport nameSt Louis Lambert International Airport
CitySt. Louis, MO
Countrythe United States

Return Airport

Destination codeBOI
Destination airport nameBoise Air Terminal Airport
CityBoise, ID
Countrythe United States


Other Resources

Please note that while we’ve worked hard to analyzed tens of millions of flights to get you this data, we do not calculate current live prices or guarantee pricing. Please see our partners using the links above for current offers.