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Idaho Falls

$242+ Cheap flights from St. Louis to Idaho Falls (STL - IDA)

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 12/18. Fares are subject to change and may not be available on all flights or dates of travel.
STL — IDA
Oct 11 — Oct 181
Sat 10/11
Sat 10/18
1 adult, Economy
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Cheap flight deals from St. Louis to Idaho Falls

Discover tips and strategies to find the most affordable flight options for your journey from St. Louis (STL) to Idaho Falls (IDA). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated September 11, 2025.

Round-trip from

$402
(United Airlines)

One-way from

$242
(Alaska Airlines)

Popular in

December

Cheapest in

January

Average price

$500
From Lambert-St Louis to Idaho Falls Fanning Field
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One-way flight from Lambert-St Louis to Idaho Falls Fanning Field
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Highest demand for flights based on searches. 3% potential increase in price ($18 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease ($15 potential savings vs. average RT price).
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Average for round-trip flights in September 2025
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Find flight deals from St. Louis to Idaho Falls

Cheapest flights from St. Louis to Idaho Falls
Explore the most affordable flight options available from St. Louis to Idaho Falls. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 11, 2025.

This United Airlines deal was found by Cheapflights users on 9/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/24:50 pmSTL - IDA
1 stop5h 02mUnited Airlines
Sun 10/55:56 pmIDA - STL
1 stop5h 02mUnited Airlines
Deal found 9/10$402
This Alaska Airlines deal was found by Cheapflights users on 9/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/17:00 amSTL - IDA
1 stop17h 59mAlaska Airlines
Tue 11/43:50 pmIDA - STL
1 stop22h 28mAlaska Airlines
Deal found 9/11$416
This United Airlines deal was found by Cheapflights users on 9/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/85:00 amSTL - IDA
2 stops9h 33mUnited Airlines
Wed 10/155:56 pmIDA - STL
1 stop5h 02mUnited Airlines
Deal found 9/10$422
This Delta deal was found by Cheapflights users on 9/8. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/275:30 pmSTL - IDA
1 stop5h 55mDelta
Wed 10/16:51 pmIDA - STL
1 stop4h 47mDelta
Deal found 9/8$426
This United Airlines deal was found by Cheapflights users on 9/9. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/239:00 amSTL - IDA
1 stop7h 11mUnited Airlines
Fri 9/265:56 pmIDA - STL
1 stop5h 02mUnited Airlines
Deal found 9/9$431
This American Airlines deal was found by Cheapflights users on 9/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/167:01 amSTL - IDA
1 stop6h 40mAmerican Airlines
Sun 10/1912:55 pmIDA - STL
1 stop6h 56mAmerican Airlines
Deal found 9/11$451
This United Airlines deal was found by Cheapflights users on 9/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/11:35 pmSTL - IDA
1 stop8h 28mUnited Airlines
Tue 11/48:30 amIDA - STL
2 stops14h 14mUnited Airlines
Deal found 9/10$460

Cheapflights Fare Finder

 
Customize your flight search to find flights from St. Louis to Idaho Falls that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated September 11, 2025.
Use the filters below to find and compare flights from St. Louis to Idaho Falls that are best for you.

Fly from

St. Louis

Fly to

Idaho Falls

Route

Depart

Return

Price

St. LouisIdaho Falls

STL - IDA

STLIDA

Lambert-St Louis

Thu 10/2

4:50 pm-8:52 pm

1 stop5h 02m

Idaho Falls Fanning Field

Sun 10/5

5:56 pm-11:58 pm

1 stop5h 02m

$402

St. LouisIdaho Falls

STL - IDA

STLIDA

Lambert-St Louis

Wed 10/8

5:15 am-9:48 am

1 stop5h 33m

Idaho Falls Fanning Field

Wed 10/15

5:56 pm-11:58 pm

1 stop5h 02m

$407

St. LouisIdaho Falls

STL - IDA

STLIDA

Lambert-St Louis

Sat 11/1

7:00 am-11:59 pm

1 stop17h 59m

Idaho Falls Fanning Field

Tue 11/4

3:50 pm-3:18 pm

1 stop22h 28m

$416

St. LouisIdaho Falls

STL - IDA

STLIDA

Lambert-St Louis

Sat 9/27

5:30 pm-10:25 pm

1 stop5h 55m

Idaho Falls Fanning Field

Wed 10/1

6:51 pm-12:38 am

1 stop4h 47m

$426

St. LouisIdaho Falls

STL - IDA

STLIDA

Lambert-St Louis

Tue 9/23

8:10 am-5:23 pm

2 stops10h 13m

Idaho Falls Fanning Field

Fri 9/26

5:56 pm-11:58 pm

1 stop5h 02m

$436

St. LouisIdaho Falls

STL - IDA

STLIDA

Lambert-St Louis

Sat 11/1

1:35 pm-9:03 pm

1 stop8h 28m

Idaho Falls Fanning Field

Tue 11/4

8:30 am-11:44 pm

2 stops14h 14m

$460

St. LouisIdaho Falls

STL - IDA

STLIDA

Lambert-St Louis

Thu 12/18

5:26 pm-12:06 am

1 stop7h 40m

$242

St. LouisIdaho Falls

STL - IDA

STLIDA

Lambert-St Louis

Tue 9/16

3:35 pm-10:39 pm

1 stop8h 04m

$265

St. LouisIdaho Falls

STL - IDA

STLIDA

Lambert-St Louis

Thu 12/18

6:15 am-12:37 pm

1 stop7h 22m

$284

St. LouisIdaho Falls

STL - IDA

STLIDA

Lambert-St Louis

Tue 9/16

12:35 pm-8:54 pm

2 stops9h 19m

$311

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/9

Showing 1-10 of 12 results
1
2

Best time to book a flight from St. Louis to Idaho Falls

Have a flexible travel schedule? Discover the best time to fly to Idaho Falls from St. Louis with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from St. Louis to Idaho Falls

What is the cheapest month to book a flight from St. Louis to Idaho Falls?

Currently, October is the cheapest month in which you can book a flight from St. Louis to Idaho Falls (average of $380). Flying from St. Louis to Idaho Falls in December is currently the most expensive (average of $578). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

How much does it cost to fly round-trip from St. Louis to Idaho Falls?

Reviews of airlines servicing Idaho Falls

Get insights into the airlines that provide service to Idaho Falls. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Idaho Falls. Reviews last updated September 11, 2025.
Peruse reviews from past customers who have flown with Delta and United Airlines from St. Louis to Idaho Falls to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Delta
8.0
Very good
7,960 reviews

Crew

8.5

Food

7.3

Overall

8.0

Boarding

8.2

Comfort

7.9

Entertainment

7.9

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!
Delta
8.0
Very good
7,960 reviews
Delta
8.0
Very good
7,960 reviews

Crew

8.5

Food

7.3

Overall

8.0

Boarding

8.2

Comfort

7.9

Entertainment

7.9

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!
United Airlines
7.4
Good
8,937 reviews
Delta
8.0
Very good
7,960 reviews

Crew

8.5

Food

7.3

Overall

8.0

Boarding

8.2

Comfort

7.9

Entertainment

7.9

Reviews

1 / 20
10.0
Excellent

Kim,May 2025

PIH - SLC

This trip was fine even with delay I had plenty of time to get connection flight!

Related info for your journey

Find useful and relevant information for your journey from St. Louis to Idaho Falls. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • How long is the flight from St. Louis to Idaho Falls?

    Airlines like United Airlines and Alaska Airlines fly from St. Louis to Idaho Falls in about 5h 02m. The time it takes to get you to your destination can typically vary by up to 12h 57m. Airlines will cover a distance of 1171 mi. Both multi-stop and nonstop flights can be found to your destination and back.

  • What are the cheapest airlines flying from St. Louis to Idaho Falls round-trip?

    Delta, at $192, was found to be the cheapest airline from St. Louis to Idaho Falls. An alternate airline flying to your destination would be United Airlines. Delta is priced at 64% lower than the current average price of a flight leaving 3 months from now.

  • What are the cheapest airlines to fly from St. Louis to Idaho Falls one-way?

    To fly one-way, consider booking your trip with Alaska Airlines, which is currently one of the cheapest options available, starting at $242. Hawaiian Airlines flights start at $265 while deals on Delta start at $284 one-way.

  • Can I find deals for flights from St. Louis to Idaho Falls that include hotel bookings?

    Yes. In addition to deals on St. Louis to Idaho Falls flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from St. Louis to Idaho Falls?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from St. Louis to Idaho Falls.

  • Can I find deals for business class flights from St. Louis to Idaho Falls?

    Yes. Cheapflights offers flight deals from St. Louis to Idaho Falls by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from St. Louis to Idaho Falls?

    Currently, October is the cheapest month in which you can book a flight from St. Louis to Idaho Falls (average of $380). Flying from St. Louis to Idaho Falls in December is currently the most expensive (average of $578). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Traveling to a place near Idaho Falls?

Book flights to Idaho Falls if you plan to visit one of these locations
Rexburg

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Top 2 airlines flying from St. Louis to Idaho Falls

Discover the top 2 airlines that operate flights from St. Louis to Idaho Falls. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated September 11, 2025.
AirlineCheapestAverageFlexibilityOn-time
DeltaCheapest$192Average$384FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$400Average$632FlexibilityNo cancel feeOn-time69%

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