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Cheap flights from St. Louis to Illinois from $65

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 6/16. 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
4:09 pm - 11:10 pm
STL
-
ORD
7h 01m
1 stop
Frontier Logo
5:13 pm - 11:59 pm
ORD
-
STL
6h 46m
1 stop
$230Frontier
Tue, Aug 11 - Wed, Aug 12
Frontier Logo
6:33 pm - 7:53 pm
STL
-
ORD
25h 20m
1 stop
Frontier Logo
1:50 pm - 8:52 am
ORD
-
STL
19h 02m
1 stop
$234Frontier
Sun, Aug 9 - Thu, Aug 20
Frontier Logo
5:06 pm - 12:24 pm
STL
-
ORD
19h 18m
2 stops
Frontier Logo
1:29 pm - 5:30 pm
ORD
-
STL
28h 01m
1 stop
$235Frontier
Wed, Jun 17 - Wed, Jun 24
American Airlines Logo
9:08 am - 10:36 am
STL
-
ORD
1h 28mnonstop
American Airlines Logo
7:04 am - 8:31 am
ORD
-
STL
1h 27mnonstop
$237American Airlines
Tue, Jul 14 - Sat, Jul 18
Southwest Logo
5:55 pm - 7:05 pm
STL
-
MDW
1h 10mnonstop
Southwest Logo
6:30 am - 7:45 am
MDW
-
STL
1h 15mnonstop
$237Southwest
Wed, Jul 1 - Sat, Jul 4
American Airlines Logo
9:09 am - 10:35 am
STL
-
ORD
1h 26mnonstop
American Airlines Logo
7:10 pm - 8:32 pm
ORD
-
STL
1h 22mnonstop
$238American Airlines
Mon, Jun 29 - Wed, Jul 1
Southwest Logo
4:00 pm - 5:05 pm
STL
-
MDW
1h 05mnonstop
Southwest Logo
6:30 am - 3:40 pm
MDW
-
STL
9h 10m
1 stop
$247Southwest
Wed, Jul 1 - Sat, Jul 4
Delta Logo
6:30 am - 12:46 pm
STL
-
MDW
6h 16m
1 stop
Delta Logo
9:17 am - 1:09 pm
MDW
-
STL
3h 52m
1 stop
$257Delta
Wed, Jun 24 - Fri, Jun 26
United Airlines Logo
1:29 pm - 5:51 pm
STL
-
DEC
4h 22m
1 stop
United Airlines Logo
6:55 pm - 10:59 pm
DEC
-
STL
4h 04m
1 stop
$379United Airlines
Wed, Sep 30 - Sat, Oct 3
United Airlines Logo
1:13 pm - 5:56 pm
STL
-
DEC
4h 43m
1 stop
United Airlines Logo
9:37 am - 11:29 pm
DEC
-
STL
13h 52m
1 stop
$449United Airlines
Mon, Jun 15 - Sun, Jun 21

Delta flights from St. Louis to Illinois

Our best Delta deals on St. Louis to Illinois flight tickets
Delta
Nov 4
STL2:18 pmLambert-St Louis
4h 22m
1 stop
ORD6:40 pmChicago O'Hare Intl
Nov 11
ORD7:05 amChicago O'Hare Intl
6h 15m
1 stop
STL1:20 pmLambert-St Louis
$218
Delta
Jun 24
STL6:30 amLambert-St Louis
6h 34m
1 stop
ORD1:04 pmChicago O'Hare Intl
Jul 6
ORD7:01 amChicago O'Hare Intl
6h 08m
1 stop
STL1:09 pmLambert-St Louis
$257
Delta
Jun 12
STL1:59 pmLambert-St Louis
6h 32m
1 stop
ORD8:31 pmChicago O'Hare Intl
Jun 16
ORD2:07 pmChicago O'Hare Intl
6h 32m
1 stop
STL8:39 pmLambert-St Louis
$268

Frontier flights from St. Louis to Illinois

Our best Frontier deals on St. Louis to Illinois flight tickets
Frontier
Aug 11
STL4:09 pmLambert-St Louis
7h 01m
1 stop
ORD11:10 pmChicago O'Hare Intl
Aug 12
ORD5:13 pmChicago O'Hare Intl
6h 46m
1 stop
STL11:59 pmLambert-St Louis
$230
Frontier
Aug 28
STL5:33 pmLambert-St Louis
14h 30m
1 stop
ORD8:03 amChicago O'Hare Intl
Aug 31
ORD9:48 pmChicago O'Hare Intl
21h 35m
1 stop
STL7:23 pmLambert-St Louis
$232
Frontier
Aug 9
STL6:33 pmLambert-St Louis
25h 20m
1 stop
ORD7:53 pmChicago O'Hare Intl
Aug 20
ORD1:50 pmChicago O'Hare Intl
19h 02m
1 stop
STL8:52 amLambert-St Louis
$234

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 May 22, 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

Tue 8/11

4:09 pm-11:10 pm

1 stop7h 01m

Chicago O'Hare Intl

Wed 8/12

5:13 pm-11:59 pm

1 stop6h 46m

$230

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Sun 8/9

6:33 pm-7:53 pm

1 stop25h 20m

Chicago O'Hare Intl

Thu 8/20

1:50 pm-8:52 am

1 stop19h 02m

$234

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Wed 6/17

5:06 pm-12:24 pm

2 stops19h 18m

Chicago O'Hare Intl

Wed 6/24

1:29 pm-5:30 pm

1 stop28h 01m

$235

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Tue 7/14

9:08 am-10:36 am

Nonstop1h 28m

Chicago O'Hare Intl

Sat 7/18

7:04 am-8:31 am

Nonstop1h 27m

$237
Quickest round-trip

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Wed 7/1

5:55 pm-7:05 pm

Nonstop1h 10m

Chicago Midway

Sat 7/4

6:30 am-7:45 am

Nonstop1h 15m

$237

St. LouisChicago

STL - ORD

STLORD

Lambert-St Louis

Mon 6/29

9:09 am-10:35 am

Nonstop1h 26m

Chicago O'Hare Intl

Wed 7/1

7:10 pm-8:32 pm

Nonstop1h 22m

$238

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Wed 7/1

4:00 pm-5:05 pm

Nonstop1h 05m

Chicago Midway

Sat 7/4

6:30 am-3:40 pm

1 stop9h 10m

$247

St. LouisChicago

STL - MDW

STLMDW

Lambert-St Louis

Wed 6/24

6:30 am-12:46 pm

1 stop6h 16m

Chicago Midway

Fri 6/26

9:17 am-1:09 pm

1 stop3h 52m

$257

St. LouisDecatur

STL - DEC

STLDEC

Lambert-St Louis

Wed 9/30

1:29 pm-5:51 pm

1 stop4h 22m

Decatur Arpt

Sat 10/3

6:55 pm-10:59 pm

1 stop4h 04m

$379

St. LouisDecatur

STL - DEC

STLDEC

Lambert-St Louis

Mon 6/15

1:13 pm-5:56 pm

1 stop4h 43m

Decatur Arpt

Sun 6/21

9:37 am-11:29 pm

1 stop13h 52m

$449

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 $61, 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 $67.

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 $604. Flights from St. Louis to Illinois on a Sunday will generally be more expensive and average around $793. 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 $573. Flights at noon are often more expensive with an average ticket price of $1,098.

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

Fly from Lambert-St Louis to Chicago Midway for the best Lambert-St Louis - Illinois flight prices

How far in advance should I book a flight from St. Louis 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 $310 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 $176 on momondo.

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

There are 4 cabin classes available to choose from on 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

$218

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 $218. The best round-trip flight deal from St. Louis to Illinois found on momondo in the last 72 hours is $337.
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
11,645 reviews
Search American Airlines flights
SouthwestPriceFrom $117Free CancellationRating
7.9
4,277 reviews
Search Southwest flights
United AirlinesPriceFrom $117Free CancellationRating
7.4
9,752 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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