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Cheap flights from St. Louis to Illinois from $59

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from St. Louis to Illinois departing on 6/30. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
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0 bags

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Find the cheapest flights from St. Louis to Illinois

Cheap round-trip flights

Enter your travel dates to find the best prices.
Frontier Logo
3:21 pm - 12:59 am
STL
-
ORD
9h 38m
1 stop
Frontier Logo
8:58 pm - 3:21 pm
ORD
-
STL
18h 23m
1 stop
$171Frontier
Mon, Apr 20 - Fri, Apr 24
Southwest Logo
11:30 am - 3:05 pm
STL
-
MDW
3h 35m
1 stop
Southwest Logo
1:30 pm - 6:50 pm
MDW
-
STL
5h 20m
1 stop
$174Southwest
Wed, May 27 - Thu, May 28
Southwest Logo
7:35 am - 12:50 pm
STL
-
ORD
5h 15m
1 stop
Southwest Logo
4:15 pm - 12:15 am
ORD
-
STL
8h 00m
1 stop
$174Southwest
Wed, May 27 - Thu, May 28
Multiple Airlines Logo
8:23 pm - 10:23 am
STL
-
ORD
14h 00m
1 stop
Multiple Airlines Logo
6:55 am - 8:55 am
ORD
-
STL
26h 00m
1 stop
$176Multiple Airlines
Wed, Apr 29 - Fri, May 8
Multiple Airlines Logo
3:21 pm - 8:05 am
STL
-
ORD
16h 44m
1 stop
Multiple Airlines Logo
6:08 pm - 6:50 am
ORD
-
STL
12h 42m
1 stop
$178Multiple Airlines
Mon, Apr 27 - Tue, Apr 28
Southwest Logo
6:40 pm - 10:15 pm
STL
-
MDW
3h 35m
1 stop
Southwest Logo
10:30 am - 6:10 pm
MDW
-
STL
7h 40m
2 stops
$179Southwest
Wed, May 6 - Sat, May 9
Delta Logo
1:02 pm - 8:16 pm
STL
-
ORD
7h 14m
1 stop
Delta Logo
6:24 am - 10:32 am
ORD
-
STL
4h 08m
1 stop
$184Delta
Tue, Apr 28 - Thu, May 7
Delta Logo
6:19 am - 12:43 pm
STL
-
MDW
6h 24m
2 stops
Delta Logo
5:21 pm - 11:36 pm
MDW
-
STL
6h 15m
1 stop
$216Delta
Sat, Apr 18 - Mon, Apr 20
United Airlines Logo
7:45 am - 8:58 am
STL
-
DEC
25h 13m
1 stop
United Airlines Logo
7:25 pm - 9:13 pm
DEC
-
STL
25h 48m
1 stop
$371United Airlines
Wed, May 6 - Sun, May 10
United Airlines Logo
9:10 am - 5:57 pm
STL
-
DEC
8h 47m
1 stop
United Airlines Logo
7:25 pm - 8:39 am
DEC
-
STL
13h 14m
1 stop
$387United Airlines
Wed, Apr 29 - Wed, May 6

Frontier flights from St. Louis to Illinois

Our best Frontier deals on St. Louis to Illinois flight tickets
Frontier
Apr 20
STL3:21 pmLambert-St Louis
9h 38m
1 stop
ORD12:59 amChicago O'Hare Intl
Apr 24
ORD8:58 pmChicago O'Hare Intl
18h 23m
1 stop
STL3:21 pmLambert-St Louis
$171
Frontier
May 1
STL7:01 pmLambert-St Louis
5h 51m
1 stop
ORD12:52 amChicago O'Hare Intl
May 3
ORD10:50 amChicago O'Hare Intl
8h 31m
1 stop
STL7:21 pmLambert-St Louis
$180
Frontier
Apr 24
STL9:58 pmLambert-St Louis
8h 10m
1 stop
ORD6:08 amChicago O'Hare Intl
Apr 26
ORD5:50 amChicago O'Hare Intl
4h 59m
1 stop
STL10:49 amLambert-St Louis
$181

United Airlines flights from St. Louis to Illinois

Our best United Airlines deals on St. Louis to Illinois flight tickets
United Airlines
May 5
STL6:30 amLambert-St Louis
1h 24m
ORD7:54 amChicago O'Hare Intl
May 6
ORD7:45 pmChicago O'Hare Intl
1h 28m
STL9:13 pmLambert-St Louis
$187
United Airlines
Apr 23
STL7:45 amLambert-St Louis
1h 26m
ORD9:11 amChicago O'Hare Intl
Apr 25
ORD10:53 amChicago O'Hare Intl
1h 29m
STL12:22 pmLambert-St Louis
$191
United Airlines
Apr 28
STL7:45 amLambert-St Louis
1h 26m
ORD9:11 amChicago O'Hare Intl
May 2
ORD9:53 pmChicago O'Hare Intl
1h 26m
STL11:19 pmLambert-St Louis
$224

momondo 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, momondo users made 832,500 searches. Data last updated April 2, 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 - ORD

STLORD

Lambert-St Louis

Mon 4/20

3:21 pm-12:59 am

1 stop9h 38m

Chicago O'Hare Intl

Fri 4/24

8:58 pm-3:21 pm

1 stop18h 23m

$171
Quickest round-trip

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Wed 5/27

11:30 am-3:05 pm

1 stop3h 35m

Chicago Midway

Thu 5/28

1:30 pm-6:50 pm

1 stop5h 20m

$174

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Wed 5/27

7:35 am-12:50 pm

1 stop5h 15m

Chicago O'Hare Intl

Thu 5/28

4:15 pm-12:15 am

1 stop8h 00m

$174

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Wed 4/29

8:23 pm-10:23 am

1 stop14h 00m

Chicago O'Hare Intl

Fri 5/8

6:55 am-8:55 am

1 stop26h 00m

$176

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Mon 4/27

3:21 pm-8:05 am

1 stop16h 44m

Chicago O'Hare Intl

Tue 4/28

6:08 pm-6:50 am

1 stop12h 42m

$178

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Wed 5/6

6:40 pm-10:15 pm

1 stop3h 35m

Chicago Midway

Sat 5/9

10:30 am-6:10 pm

2 stops7h 40m

$179

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Tue 4/28

1:02 pm-8:16 pm

1 stop7h 14m

Chicago O'Hare Intl

Thu 5/7

6:24 am-10:32 am

1 stop4h 08m

$184

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Sat 4/18

6:19 am-12:43 pm

2 stops6h 24m

Chicago Midway

Mon 4/20

5:21 pm-11:36 pm

1 stop6h 15m

$216

St. LouisDecatur

STL - DEC

STLDEC

Lambert-St Louis

Wed 5/6

7:45 am-8:58 am

1 stop25h 13m

Decatur Arpt

Sun 5/10

7:25 pm-9:13 pm

1 stop25h 48m

$371

St. LouisDecatur

STL - DEC

STLDEC

Lambert-St Louis

Wed 4/29

9:10 am-5:57 pm

1 stop8h 47m

Decatur Arpt

Wed 5/6

7:25 pm-8:39 am

1 stop13h 14m

$387

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first
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See travel insights to Illinois from

How to get the cheapest flight ticket from St. Louis to Illinois

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

What is the cheapest month to fly to Illinois?

The cheapest month to fly to Illinois from St. Louis is in August. Flight prices, which tend to average around $205, are often lower during this time because this is during the off-season. If you aren’t able to travel to Illinois during the month of August, then flying in September is also cheap. Prices for this month can be found on momondo for an average of $224.

What is the cheapest day to depart on your flight to Illinois?

The cheapest day to depart from St. Louis to Illinois is on a Friday when prices can be found for as low as $615. Flights from St. Louis to Illinois on a Saturday will generally be more expensive and average around $802. Keep in mind that these prices on both days could fluctuate depending on the season and the demand.

What is the cheapest time of day to depart on your flight to Illinois?

Our most recent data shows that the best time of day to fly to Illinois is in the morning. Flights from St. Louis to Illinois during this time can be as low as $569. Flights at noon are often more expensive with an average ticket price of $1,094.

What is the cheapest Lambert-St Louis to Illinois flight route?

Fly from Lambert-St Louis to Chicago O'Hare Intl for the best Lambert-St Louis - Illinois flight prices

How far in advance should I book a flight to Illinois?

You are more likely to see cheaper flights to Illinois from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to Illinois for around $295 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Illinois from St. Louis for as low as $183 on momondo.

What cabin class options are available on Lambert-St Louis to Illinois flights?

There are 4 cabin classes available to choose from on Lambert-St Louis to Illinois flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on St. Louis to Illinois flights?

No. A direct flight is the cheapest option for a flight between St. Louis to Illinois.

Cheap St. Louis to Illinois flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from St. Louis to Illinois

Best Price Found

$223

Fastest flight time

1h 05m

Direct flights

Every day

Airports in Illinois

98 airports
The best one-way flight to Illinois from St. Louis in the past 72 hours is $223. The best round-trip flight deal from St. Louis to Illinois found on momondo in the last 72 hours is $335.
The fastest flight from St. Louis to Illinois takes 1h 05m
Direct flights go from St. Louis to Illinois every day.
There are 98 airports in Illinois. From St. Louis there are direct flights to Chicago O'Hare Intl (ORD), Chicago Midway (MDW).
Search flight deals

Frequently asked questions about flying from St. Louis to Illinois

  • When did momondo last update prices for flights from Lambert-St Louis Airport to Illinois?

    Prices for flights from Lambert-St Louis Airport to Illinois refresh daily.

  • How many operators does momondo search for flights from Lambert-St Louis Airport to Illinois?

  • How old do you have to be to fly from Lambert-St Louis Airport to Illinois?

    Although the minimum age for a child to fly alone is five, airlines that offer an unaccompanied minor (UMNR) service may have their own age limits, which could be impacted by factors such as flight length, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Lambert-St Louis Airport to Illinois.

  • What documentation or ID do you need to fly to Illinois?

    The travel and health documents you'll need for your trip to Illinois may differ based on your itinerary and personal situation. Typically, you should have several documents on hand, such as a national ID card or driver's license and a passport that is valid for six months after your intended arrival at Illinois. It is always advisable to seek advice from your airline or a trusted third party, such as IATA.

  • What is the most popular plane model from St. Louis to Illinois?

Best airlines flying from St. Louis to Illinois

Compare and see reviews for airlines that fly from St. Louis to Illinois with momondo
Airline
Rating
Free Cancellation
Price
American AirlinesPriceFrom $97Free CancellationRating
7.1
11,548 reviews
Search American Airlines flights
SouthwestPriceFrom $117Free CancellationRating
8.0
4,337 reviews
Search Southwest flights
United AirlinesPriceFrom $125Free CancellationRating
7.4
9,535 reviews
Search United Airlines flights
Southern / MokulelePriceFrom $140Free CancellationRating
0.0
0 reviews
Search Southern / Mokulele flights

Why use momondo?

Why should I use momondo to find a flight deal from St. Louis to Illinois?

momondo compares prices from hundreds of airlines and agents so you can find and book the best deal on flights from St. Louis to Illinois. Millions of users trust and use momondo every year so you are in good hands.

Can I find flights from St. Louis to Illinois with flexible booking policies on momondo?

Flights from St. Louis to Illinois with flexible booking policies can be found by using the search form above and then selecting our dedicated flexible booking filter, which will highlight only the flights where this policy is applied.

How can momondo help me find flights from St. Louis to Illinois?

Once you have performed a search in the form on the page, momondo provides useful filters and insights. We can show you the cheapest days and times to fly as well as help filter your options to help you make an informed choice when booking flights to Illinois from St. Louis.

I’m not ready to book a flight from St. Louis to Illinois right now. Can momondo alert me if prices change?

Yes. momondo can track prices for St. Louis to Illinois flights and alert you when they change. Perform a search to set up the price alert. All that is required is a valid email address.

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