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$70+ 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 4/24. Fares are subject to change and may not be available on all flights or dates of travel.
STL — ORD
Apr 28 — May 51
Tue 4/28
Tue 5/5
1 adult, Economy
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Cheap 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 March 29, 2026.

This Kiwi.com deal was found by Cheapflights users on 3/27. 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.
Thu 4/3011:21 am
STL
-
ORD
1 stop23h 02m
Multiple Airlines
Sun 5/311:28 am
ORD
-
STL
1 stop19h 22m
Multiple Airlines
Deal found 3/27$178
This Frontier deal was found by Cheapflights users on 3/24. 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.
Tue 4/711:21 am
STL
-
ORD
1 stop11h 18m
Frontier
Thu 4/94:21 pm
ORD
-
STL
1 stop7h 04m
Frontier
Deal found 3/24$180
This Frontier deal was found by Cheapflights users on 3/24. 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 4/1611:25 am
STL
-
MDW
1 stop10h 54m
Frontier
Mon 4/209:14 am
MDW
-
STL
1 stop14h 05m
Frontier
Deal found 3/24$181
This Frontier deal was found by Cheapflights users on 3/27. 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.
Fri 5/154:19 pm
STL
-
ORD
1 stop6h 54m
Frontier
Tue 5/196:55 am
ORD
-
STL
1 stop10h 38m
Frontier
Deal found 3/27$181
This Frontier deal was found by Cheapflights users on 3/24. 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 4/1611:25 am
STL
-
ORD
1 stop11h 14m
Frontier
Mon 4/206:00 am
ORD
-
STL
1 stop17h 19m
Frontier
Deal found 3/24$182
This Southwest deal was found by Cheapflights users on 3/27. 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.
Thu 4/239:40 pm
STL
-
MDW
Nonstop1h 05m
Southwest
Sat 4/256:30 pm
MDW
-
STL
Nonstop1h 15m
Southwest
Deal found 3/27$191
This United Airlines deal was found by Cheapflights users on 3/27. 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 4/237:45 am
STL
-
ORD
Nonstop1h 26m
United Airlines
Sat 4/258:20 pm
ORD
-
STL
Nonstop1h 32m
United Airlines
Deal found 3/27$191
This CheapOair deal was found by Cheapflights users on 3/26. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/244:59 pm
STL
-
ORD
1 stop22h 24m
Frontier
Sun 4/265:50 am
ORD
-
STL
1 stop4h 59m
Frontier
Deal found 3/26$192
This Kiwi.com deal was found by Cheapflights users on 3/28. 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.
Mon 5/48:23 pm
STL
-
ORD
1 stop11h 32m
Frontier
Wed 5/61:59 pm
ORD
-
STL
1 stop26h 55m
Frontier
Deal found 3/28$195
This Kiwi.com deal was found by Cheapflights users on 3/24. 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.
Tue 5/56:41 pm
STL
-
MDW
1 stop27h 21m
Frontier
Tue 5/126:00 am
MDW
-
STL
1 stop26h 55m
Frontier
Deal found 3/24$196
This Kiwi.com deal was found by Cheapflights users on 3/24. 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.
Tue 5/56:41 pm
STL
-
ORD
1 stop13h 14m
Frontier
Tue 5/126:55 am
ORD
-
STL
1 stop26h 00m
Frontier
Deal found 3/24$196
This Kiwi.com deal was found by Cheapflights users on 3/27. 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.
Wed 4/228:23 pm
STL
-
ORD
1 stop14h 00m
Multiple Airlines
Fri 4/244:28 pm
ORD
-
STL
1 stop14h 22m
Multiple Airlines
Deal found 3/27$199

Find 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 March 29, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$178
(Kiwi.com)

One-way from

$70
(Frontier)

Popular in

January

Cheapest in

August

Average price

$310

Good round-trip deal

$327 or less

Good one-way deal

$201 or less
Provider with most accurate pricing for Lambert-St Louis-Chicago (CHI) flight deals.
Search Deals
Provider most trusted by Cheapflights users for Lambert-St Louis-Chicago (CHI) flights.
Search Deals
From Lambert-St Louis to Illinois
Search Deals
One-way flight from Lambert-St Louis to Illinois
Search Deals
Highest demand for flights based on searches. 28% potential increase in price ($122 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 6% potential price decrease ($18 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in March 2026
Search Deals
Price to beat on a round-trip flight from Lambert-St Louis to Illinois.
Search Deals
Price to beat on a one-way flight from Lambert-St Louis to Illinois.
Search Deals

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 March 29, 2026.
Use the filters below to find and compare flights from St. Louis to Illinois that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Sat 4/18

6:55 pm-8:05 pm

Nonstop1h 10m

Chicago Midway

Mon 4/20

9:00 am-10:15 am

Nonstop1h 15m

$191

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Mon 5/11

1:45 pm-2:55 pm

Nonstop1h 10m

Chicago Midway

Mon 5/18

7:50 am-9:05 am

Nonstop1h 15m

$191

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Sat 5/2

6:48 am-12:43 pm

1 stop5h 55m

Chicago Midway

Mon 5/4

7:16 pm-11:13 pm

1 stop3h 57m

$211

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Wed 5/20

6:45 am-1:01 pm

1 stop6h 16m

Chicago O'Hare Intl

Wed 5/27

6:24 am-10:32 am

1 stop4h 08m

$211

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Wed 5/13

6:35 am-3:00 pm

1 stop8h 25m

Chicago O'Hare Intl

Sat 5/23

1:55 pm-7:10 pm

1 stop5h 15m

$211

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Sat 5/2

1:03 pm-6:48 pm

1 stop5h 45m

Chicago O'Hare Intl

Mon 5/4

7:09 pm-11:13 pm

1 stop4h 04m

$211

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Sat 4/25

6:10 am-2:15 pm

2 stops8h 05m

Chicago Midway

Sat 5/2

8:35 am-4:25 pm

2 stops7h 50m

$221

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Tue 5/5

11:42 am-4:42 pm

1 stop5h 00m

Chicago O'Hare Intl

Wed 5/6

7:10 am-11:56 am

1 stop4h 46m

$233

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Tue 4/14

6:19 am-12:45 pm

2 stops6h 26m

Chicago O'Hare Intl

Wed 4/15

9:50 am-3:32 pm

1 stop5h 42m

$238

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Tue 4/21

12:23 pm-8:40 pm

2 stops8h 17m

Chicago O'Hare Intl

Tue 5/5

7:00 am-4:50 pm

2 stops9h 50m

$243

Flights are sorted by cheapest round-trip flights first.

Deals found on 3/26

Showing 1-10 of 44 resultsSorted by cheapest first
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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 March is currently the most expensive (average of $172). 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 March 29, 2026.

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 31% 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 March 28, 2026.

Travelers seeking maximum savings on their St. Louis to Illinois flight should consider departing on Tuesday at noon when fares are most often at their lowest. Tuesday evenings 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 March 29, 2026.

The most flights from STL to USIL are scheduled on a Saturday (59 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (6 on average).

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

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 March 29, 2026.
See what other customers who have flown with Southwest,United Airlines, andAmerican 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
4,331 reviews

Food

7.0

Comfort

8.0

Crew

8.6

Entertainment

7.5

Overall

8.0

Boarding

8.1

Reviews

1 / 20
2.0
Mediocre

Dominic,Mar 2026

MCO - SMF

I had to try and sleep on the floor of the Austin airport. I spent 12 hours there. The airline policies were so poor, that a near violent argument broke out between the people in front of me and the flight attendants - making for a super stressful situation at 30,000 feet. Garbage airline choice by Kayak Garbage idea to book a flight with a layover. Next time I will pay for a quality booking myself, and somehow force the company to reimburse it.
Southwest
8.0
Very good
4,331 reviews
Southwest
8.0
Very good
4,331 reviews

Food

7.0

Comfort

8.0

Crew

8.6

Entertainment

7.5

Overall

8.0

Boarding

8.1

Reviews

1 / 20
2.0
Mediocre

Dominic,Mar 2026

MCO - SMF

I had to try and sleep on the floor of the Austin airport. I spent 12 hours there. The airline policies were so poor, that a near violent argument broke out between the people in front of me and the flight attendants - making for a super stressful situation at 30,000 feet. Garbage airline choice by Kayak Garbage idea to book a flight with a layover. Next time I will pay for a quality booking myself, and somehow force the company to reimburse it.
United Airlines
7.4
Good
9,509 reviews
Southwest
8.0
Very good
4,331 reviews

Food

7.0

Comfort

8.0

Crew

8.6

Entertainment

7.5

Overall

8.0

Boarding

8.1

Reviews

1 / 20
2.0
Mediocre

Dominic,Mar 2026

MCO - SMF

I had to try and sleep on the floor of the Austin airport. I spent 12 hours there. The airline policies were so poor, that a near violent argument broke out between the people in front of me and the flight attendants - making for a super stressful situation at 30,000 feet. Garbage airline choice by Kayak Garbage idea to book a flight with a layover. Next time I will pay for a quality booking myself, and somehow force the company to reimburse it.
American Airlines
7.1
Good
11,520 reviews
Southwest
8.0
Very good
4,331 reviews

Food

7.0

Comfort

8.0

Crew

8.6

Entertainment

7.5

Overall

8.0

Boarding

8.1

Reviews

1 / 20
2.0
Mediocre

Dominic,Mar 2026

MCO - SMF

I had to try and sleep on the floor of the Austin airport. I spent 12 hours there. The airline policies were so poor, that a near violent argument broke out between the people in front of me and the flight attendants - making for a super stressful situation at 30,000 feet. Garbage airline choice by Kayak Garbage idea to book a flight with a layover. Next time I will pay for a quality booking myself, and somehow force the company to reimburse it.
Southern / Mokulele
6.5
Okay
27 reviews
Southwest
8.0
Very good
4,331 reviews

Food

7.0

Comfort

8.0

Crew

8.6

Entertainment

7.5

Overall

8.0

Boarding

8.1

Reviews

1 / 20
2.0
Mediocre

Dominic,Mar 2026

MCO - SMF

I had to try and sleep on the floor of the Austin airport. I spent 12 hours there. The airline policies were so poor, that a near violent argument broke out between the people in front of me and the flight attendants - making for a super stressful situation at 30,000 feet. Garbage airline choice by Kayak Garbage idea to book a flight with a layover. Next time I will pay for a quality booking myself, and somehow force the company to reimburse it.

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 $191. 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 Southern / Mokulele. According to our data, you can fly for as low as $34. Users have also found prices from $45 and $48 on Southwest and American 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: Republic Airways (82%), Turkish Airlines (74%), Japan Airlines (74%).

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

    The cheapest flight price from St. Louis to Illinois is $129. On average you can expect to pay $888. The most popular route, (Lambert-St Louis - Chicago O'Hare Intl), can usually be booked for $181.

  • 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 March is currently the most expensive (average of $172). 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 March 29, 2026.
AirlineCheapestAverageFlexibilityOn-time
American AirlinesCheapest$97Average$293FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$117Average$340FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$125Average$346FlexibilityNo cancel feeOn-time69%
Southern / MokuleleCheapest$140Average$198FlexibilityNo cancel feeOn-timeN/A

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