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$49+ Cheap flights from St. Louis (STL) to Illinois

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 12/24. Fares are subject to change and may not be available on all flights or dates of travel.
STL — ORD
Dec 13 — Dec 201
Sat 12/13
Sat 12/20
1 adult, Economy
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Cheap flight deals from St. Louis to Illinois

Keep the following information in mind while searching for St. Louis to Illinois flight deals. Data was last updated November 13, 2025.

Most accurate provider

Justfly.com
3 stars

Most trusted provider

Justfly.com
3 stars

Round-trip from

$97
(Southwest)

One-way from

$49
(Southwest)

Popular in

November

Cheapest in

August

Average price

$314

Good round-trip deal

$307 or less

Good one-way deal

$149 or less
Provider with most accurate pricing for Lambert-St Louis-Chicago (CHI) flight deals.
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Provider most trusted by Cheapflights users for Lambert-St Louis-Chicago (CHI) flights.
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From Lambert-St Louis to Illinois
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One-way flight from Lambert-St Louis to Illinois
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Highest demand for flights based on searches. 6% potential increase in price ($16 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease ($6 potential savings vs. average RT price).
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Average for round-trip flights in November 2025
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Price to beat on a round-trip flight from Lambert-St Louis to Illinois.
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Price to beat on a one-way flight from Lambert-St Louis to Illinois.
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Find flight deals from St. Louis to Illinois

Cheapest flights from St. Louis to Illinois
Explore the most affordable flight options available from St. Louis to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on November 13, 2025.

This Southwest deal was found by Cheapflights users on 11/12. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/314:25 pmSTL - MDW
Nonstop1h 10mSouthwest
Thu 1/18:25 amMDW - STL
Nonstop1h 15mSouthwest
Deal found 11/12$97
This American Airlines deal was found by Cheapflights users on 11/12. 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.
Wed 12/314:53 pmSTL - ORD
Nonstop1h 44mAmerican Airlines
Thu 1/17:07 amORD - STL
Nonstop1h 28mAmerican Airlines
Deal found 11/12$97
This American Airlines deal was found by Cheapflights users on 11/11. 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.
Wed 12/316:00 amSTL - ORD
Nonstop1h 30mAmerican Airlines
Wed 1/77:50 pmORD - STL
Nonstop1h 25mAmerican Airlines
Deal found 11/11$107
This American Airlines deal was found by Cheapflights users on 11/12. 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.
Tue 12/165:40 pmSTL - ORD
Nonstop1h 40mAmerican Airlines
Thu 12/257:07 amORD - STL
Nonstop1h 28mAmerican Airlines
Deal found 11/12$108
This Frontier deal was found by Cheapflights users on 11/11. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/412:04 pmSTL - ORD
1 stop5h 23mFrontier
Thu 12/119:53 pmORD - STL
1 stop13h 29mFrontier
Deal found 11/11$110
This Frontier deal was found by Cheapflights users on 11/11. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/412:04 pmSTL - MDW
1 stop10h 08mFrontier
Mon 12/83:10 pmMDW - STL
1 stop7h 23mFrontier
Deal found 11/11$111
This Frontier deal was found by Cheapflights users on 11/11. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/412:04 pmSTL - ORD
1 stop10h 20mFrontier
Mon 12/82:26 pmORD - STL
1 stop8h 07mFrontier
Deal found 11/11$111
This Frontier deal was found by Cheapflights users on 11/13. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/412:04 pmSTL - ORD
1 stop10h 20mFrontier
Sat 12/62:26 pmORD - STL
1 stop18h 33mFrontier
Deal found 11/13$112
This Southwest deal was found by Cheapflights users on 11/12. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/34:25 pmSTL - MDW
Nonstop1h 10mSouthwest
Wed 12/39:05 pmMDW - STL
Nonstop1h 15mSouthwest
Deal found 11/12$117
This United Airlines deal was found by Cheapflights users on 11/12. 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 12/105:27 pmSTL - ORD
Nonstop1h 23mUnited Airlines
Wed 12/1710:50 amORD - STL
Nonstop1h 25mUnited Airlines
Deal found 11/12$117
This Frontier deal was found by Cheapflights users on 11/11. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/412:04 pmSTL - ORD
1 stop5h 23mFrontier
Thu 12/49:53 pmORD - STL
1 stop13h 29mFrontier
Deal found 11/11$130
This Kiwi.com deal was found by Cheapflights users on 11/13. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/1210:42 amSTL - ORD
1 stop25h 12mFrontier
Mon 12/2212:39 pmORD - STL
1 stop21h 01mFrontier
Deal found 11/13$132

Cheapflights Fare Finder

 
Customize your flight search to find flights from St. Louis to Illinois 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 November 13, 2025.
Use the filters below to find and compare flights from St. Louis to Illinois that are best for you.

Fly from

St. Louis

Fly to

Illinois

Route

Depart

Return

Price

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Wed 12/31

4:25 pm-5:35 pm

Nonstop1h 10m

Chicago Midway

Thu 1/1

5:00 am-10:10 am

1 stop5h 10m

$107

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Thu 12/4

12:04 pm-10:12 pm

1 stop10h 08m

Chicago Midway

Mon 12/8

3:10 pm-10:33 pm

1 stop7h 23m

$111

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Wed 12/10

5:27 pm-6:50 pm

Nonstop1h 23m

Chicago O'Hare Intl

Wed 12/17

10:50 am-12:15 pm

Nonstop1h 25m

$117

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Tue 12/16

7:00 am-8:10 am

Nonstop1h 10m

Chicago Midway

Tue 12/16

5:15 pm-6:30 pm

Nonstop1h 15m

$117

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Tue 12/9

10:00 am-11:29 am

Nonstop1h 29m

Chicago O'Hare Intl

Tue 12/16

10:50 am-12:15 pm

Nonstop1h 25m

$117

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Wed 12/3

2:15 pm-3:20 pm

Nonstop1h 05m

Chicago Midway

Thu 12/4

9:05 pm-10:20 pm

Nonstop1h 15m

$144

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Sat 12/13

5:27 pm-6:50 pm

Nonstop1h 23m

Chicago O'Hare Intl

Wed 12/17

1:00 pm-2:25 pm

Nonstop1h 25m

$144

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Thu 2/12

5:00 pm-10:35 pm

1 stop5h 35m

Chicago Midway

Sun 2/15

5:50 am-7:10 am

Nonstop1h 20m

$144

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Wed 12/3

2:15 pm-3:20 pm

Nonstop1h 05m

Chicago Midway

Mon 1/19

11:35 am-5:00 pm

1 stop5h 25m

$154

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Wed 12/10

11:40 am-4:34 pm

1 stop4h 54m

Chicago Midway

Wed 12/17

12:50 pm-6:33 pm

1 stop5h 43m

$157

Flights are sorted by cheapest round-trip flights first.

Deals found on 11/11

Showing 1-10 of 44 results
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Best time to book a flight from St. Louis to Illinois

Have a flexible travel schedule? Discover the best time to fly to Illinois 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 Illinois

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

Currently, November is the cheapest month in which you can book a flight from St. Louis to Illinois (average of $77). Flying from St. Louis to Illinois in August is currently the most expensive (average of $159). 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.

What is the cheapest time of day to fly from STL to IL?

Find hourly flight availability from St. Louis to Illinois. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated November 13, 2025.

When flying from St. Louis to Illinois, the time of day you fly usually plays a role in the price. Save by searching for a flight in the morning, which can drop the price by up to 27% versus a flight at noon.

What is the cheapest day to fly from St. Louis to Illinois?

Use this chart to determine the cheapest time to fly round-trip from St. Louis to Illinois. Price data was last updated on December 16, 2024.

Travelers seeking maximum savings on their St. Louis to Illinois flight should consider departing on Saturday mornings when fares are most often at their lowest. Tuesday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from St. Louis to Illinois

Explore weekly flight availability from St. Louis to Illinois. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated November 13, 2025.

The most flights from STL to USIL are scheduled on a Monday (70 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (52 on average).

Reviews of airlines servicing Illinois

Get insights into the airlines that provide service to Illinois. 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 Illinois. Reviews last updated November 13, 2025.
See what other customers who have flown with Southwest, United Airlines, and American Airlines from St. Louis to Illinois have to say. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,242 reviews

Comfort

8.0

Crew

8.6

Food

7.0

Boarding

8.1

Entertainment

7.5

Overall

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Southwest
8.0
Very good
4,242 reviews
Southwest
8.0
Very good
4,242 reviews

Comfort

8.0

Crew

8.6

Food

7.0

Boarding

8.1

Entertainment

7.5

Overall

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
United Airlines
7.4
Good
9,017 reviews
Southwest
8.0
Very good
4,242 reviews

Comfort

8.0

Crew

8.6

Food

7.0

Boarding

8.1

Entertainment

7.5

Overall

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
American Airlines
7.2
Good
11,051 reviews
Southwest
8.0
Very good
4,242 reviews

Comfort

8.0

Crew

8.6

Food

7.0

Boarding

8.1

Entertainment

7.5

Overall

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Southern / Mokulele
6.4
Okay
27 reviews
Southwest
8.0
Very good
4,242 reviews

Comfort

8.0

Crew

8.6

Food

7.0

Boarding

8.1

Entertainment

7.5

Overall

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines

Related info for your journey

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

  • What airport do you fly from for flights from St. Louis to Illinois?

    Located just 12.7 mi from the city center, Lambert-St Louis (STL) is the airport most travelers will use when flying to Illinois from St. Louis.

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

    A quick flight from St. Louis to Illinois can take about 1h 10m. Southwest provides one of the quickest options available for as low as $107. St. Louis and Illinois are separated by a distance of 251 mi. This flight may include one or multiple stops.

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

    For one-way options, check prices for Southwest. According to our data, you can fly for as low as $49. Users have also found prices from $55 and $59 on Frontier and United Airlines, respectively.

  • What are the most popular routes from St. Louis to Illinois?

    Most travelers choose Lambert-St Louis - Chicago O'Hare Intl, Lambert-St Louis - Chicago Midway or Lambert-St Louis - Decatur Arpt when deciding on the best route from St. Louis to Illinois.

  • What are the most reliable airlines from St. Louis to Illinois?

    Looking for the most reliable airlines to get you to your destination on time? Our data shows these are most likely to get you from St. Louis to Illinois on time: Cathay Pacific (90%), Austrian Airlines (88%), Envoy Air (87%).

  • What are the cheapest flights from St. Louis to Illinois?

    The cheapest flight price from St. Louis to Illinois is $125. On average you can expect to pay $1,020. The most popular route, (Lambert-St Louis - Chicago O'Hare Intl), can usually be booked for $97.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from St. Louis to Illinois 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 Illinois?

    Currently, November is the cheapest month in which you can book a flight from St. Louis to Illinois (average of $77). Flying from St. Louis to Illinois in August is currently the most expensive (average of $159). 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.

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Alternative routes for St. Louis to Illinois

See prices for flight routes from nearby airports that may be better suited for you.
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Top 4 airlines flying from St. Louis to Illinois

Discover the top 4 airlines that operate flights from St. Louis to Illinois. 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 November 13, 2025.
AirlineCheapestAverageFlexibilityOn-time
American AirlinesCheapest$112Average$282FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$115Average$311FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$117Average$325FlexibilityNo cancel feeOn-time63%
Southern / MokuleleCheapest$140Average$221FlexibilityNo cancel feeOn-timeN/A

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