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Cheap flights from Illinois to St. Louis from $49

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from Illinois to St. Louis departing on 11/3. 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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Find the cheapest flights from Illinois to St. Louis

Cheap round-trip flights

Southwest Logo
7:40 pm - 8:50 pmMDW-STL
1h 10mnonstop
Southwest Logo
5:25 am - 6:35 amSTL-MDW
1h 10mnonstop
$97Southwest
Find Deal
Sat, Sep 20 - Mon, Sep 22
United Airlines Logo
2:20 pm - 3:44 pmORD-STL
1h 24mnonstop
United Airlines Logo
5:28 pm - 6:53 pmSTL-ORD
1h 25mnonstop
$97United Airlines
Find Deal
Tue, Oct 21 - Sat, Oct 25
American Airlines Logo
8:00 am - 9:26 amORD-STL
1h 26mnonstop
American Airlines Logo
3:56 pm - 5:29 pmSTL-ORD
1h 33mnonstop
$98American Airlines
Find Deal
Sat, Sep 20 - Mon, Sep 22
American Airlines Logo
8:00 am - 9:26 amORD-STL
1h 26mnonstop
American Airlines Logo
7:23 am - 8:45 amSTL-ORD
1h 22mnonstop
$99American Airlines
Find Deal
Sat, Sep 20 - Mon, Sep 22
Frontier Logo
5:25 am - 1:17 pmORD-STL
7h 52m1 stop
Frontier Logo
4:29 pm - 12:11 amSTL-ORD
7h 42m1 stop
$139Frontier
Find Deal
Fri, Nov 14 - Fri, Nov 14
Frontier Logo
5:10 am - 3:04 pmORD-STL
9h 54m1 stop
Frontier Logo
4:00 pm - 12:10 amSTL-ORD
8h 10m1 stop
$143Frontier
Find Deal
Mon, Sep 22 - Thu, Sep 25
Logo
2:20 pm - 3:44 pmORD-STL
1h 24mnonstop
Logo
1:00 pm - 4:19 pmSTL-ORD
3h 19m1 stop
$164
Find Deal
Sat, Sep 20 - Mon, Sep 22
Southern / Mokulele Logo
8:15 am - 12:00 pmORD-STL
3h 45m1 stop
Southern / Mokulele Logo
5:15 pm - 8:39 pmSTL-ORD
3h 24m1 stop
$169Southern / Mokulele
Find Deal
Fri, Sep 26 - Sun, Sep 28
Southern / Mokulele Logo
1:10 pm - 4:35 pmORD-STL
3h 25m1 stop
Southern / Mokulele Logo
1:00 pm - 7:24 amSTL-ORD
18h 24m1 stop
$171Southern / Mokulele
Find Deal
Wed, Oct 1 - Thu, Oct 2
Logo
8:15 am - 12:00 pmORD-STL
3h 45m1 stop
Logo
7:55 pm - 9:37 amSTL-ORD
13h 42m1 stop
$180
Find Deal
Sun, Sep 21 - Sat, Sep 27

Southwest flights from Illinois to St. Louis

Our best Southwest deals on Illinois to St. Louis flight tickets
Southwest
Sep 20
MDW7:40 pmChicago Midway
1h 10m
STL8:50 pmLambert-St Louis
Sep 22
STL5:25 amLambert-St Louis
1h 10m
MDW6:35 amChicago Midway
$97
Find similar
Southwest
Sep 20
MDW9:35 amChicago Midway
5h 10m
1 stop
STL2:45 pmLambert-St Louis
Sep 22
STL7:20 pmLambert-St Louis
1h 05m
MDW8:25 pmChicago Midway
$107
Find similar
Southwest
Sep 20
MDW12:45 pmChicago Midway
7h 05m
1 stop
STL7:50 pmLambert-St Louis
Sep 22
STL2:00 pmLambert-St Louis
5h 50m
1 stop
MDW7:50 pmChicago Midway
$117
Find similar

United Airlines flights from Illinois to St. Louis

Our best United Airlines deals on Illinois to St. Louis flight tickets
United Airlines
Oct 21
ORD2:20 pmChicago O'Hare Intl
1h 24m
STL3:44 pmLambert-St Louis
Oct 25
STL5:28 pmLambert-St Louis
1h 25m
ORD6:53 pmChicago O'Hare Intl
$97
Find similar
United Airlines
Sep 25
ORD2:20 pmChicago O'Hare Intl
1h 24m
STL3:44 pmLambert-St Louis
Sep 29
STL12:25 pmLambert-St Louis
1h 25m
ORD1:50 pmChicago O'Hare Intl
$152
Find similar
United Airlines
Sep 23
ORD4:55 pmChicago O'Hare Intl
1h 28m
STL6:23 pmLambert-St Louis
Sep 24
STL7:04 pmLambert-St Louis
1h 32m
ORD8:36 pmChicago O'Hare Intl
$155
Find similar

momondo Fare Finder

 
Customize your flight search to find flights from Illinois to St. Louis 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 August 31, 2025.
Use the filters below to find and compare flights from Illinois to St. Louis that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

ChicagoSt. Louis

MDW - STL

MDWSTL

Chicago Midway

Sat 9/20

7:40 pm-8:50 pm

Nonstop1h 10m

Lambert-St Louis

Mon 9/22

5:25 am-6:35 am

Nonstop1h 10m

$97

ChicagoSt. Louis

ORD - STL

ORDSTL

Chicago O'Hare Intl

Tue 10/21

2:20 pm-3:44 pm

Nonstop1h 24m

Lambert-St Louis

Sat 10/25

5:28 pm-6:53 pm

Nonstop1h 25m

$97

ChicagoSt. Louis

ORD - STL

ORDSTL

Chicago O'Hare Intl

Sat 9/20

8:00 am-9:26 am

Nonstop1h 26m

Lambert-St Louis

Mon 9/22

3:56 pm-5:29 pm

Nonstop1h 33m

$98

ChicagoSt. Louis

ORD - STL

ORDSTL

Chicago O'Hare Intl

Sat 9/20

8:00 am-9:26 am

Nonstop1h 26m

Lambert-St Louis

Mon 9/22

7:23 am-8:45 am

Nonstop1h 22m

$99

ChicagoSt. Louis

ORD - STL

ORDSTL

Chicago O'Hare Intl

Fri 11/14

5:25 am-1:17 pm

1 stop7h 52m

Lambert-St Louis

Fri 11/14

4:29 pm-12:11 am

1 stop7h 42m

$139

ChicagoSt. Louis

ORD - STL

ORDSTL

Chicago O'Hare Intl

Mon 9/22

5:10 am-3:04 pm

1 stop9h 54m

Lambert-St Louis

Thu 9/25

4:00 pm-12:10 am

1 stop8h 10m

$143

ChicagoSt. Louis

ORD - STL

ORDSTL

Chicago O'Hare Intl

Sat 9/20

2:20 pm-3:44 pm

Nonstop1h 24m

Lambert-St Louis

Mon 9/22

1:00 pm-4:19 pm

1 stop3h 19m

$164

ChicagoSt. Louis

ORD - STL

ORDSTL

Chicago O'Hare Intl

Fri 9/26

8:15 am-12:00 pm

1 stop3h 45m

Lambert-St Louis

Sun 9/28

5:15 pm-8:39 pm

1 stop3h 24m

$169

ChicagoSt. Louis

ORD - STL

ORDSTL

Chicago O'Hare Intl

Wed 10/1

1:10 pm-4:35 pm

1 stop3h 25m

Lambert-St Louis

Thu 10/2

1:00 pm-7:24 am

1 stop18h 24m

$171

ChicagoSt. Louis

ORD - STL

ORDSTL

Chicago O'Hare Intl

Sun 9/21

8:15 am-12:00 pm

1 stop3h 45m

Lambert-St Louis

Sat 9/27

7:55 pm-9:37 am

1 stop13h 42m

$180

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 St. Louis from

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

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 St. Louis?

In general, September is the cheapest month to fly from Illinois to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $263. The month of April is another great option to travel to St. Louis, with average flight prices from Illinois averaging around $268.

What is the cheapest day to depart on your flight to St. Louis?

The cheapest day to depart on your flight to St. Louis is on a Thursday when prices can be found for as low as $310. This is often the case because there is less demand to fly during this day of the week. If your travel schedule is flexible, try to avoid departing on a Monday because tickets tend to average around $510. These prices are subject to change though, so be sure to set up a Price Alert for flights to St. Louis.

What is the cheapest time of day to depart on your flight to St. Louis?

Flying to St. Louis from Illinois in the evening is the least expensive time of day to depart. momondo users have found prices as low as $290 when looking at flights departing in the evening. In the morning is when there is more demand to fly to St. Louis, so prices are often more expensive at around $430 per ticket.

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

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

How far in advance should I book a flight to St. Louis?

You are more likely to see cheaper flights to St. Louis from Illinois when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around $273 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to St. Louis from Illinois for as low as $118 on momondo.

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

There are 4 cabin classes available to choose from on Illinois to Lambert-St Louis 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 Illinois to St. Louis flights?

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

Cheap Illinois to St. Louis flight deals and tips

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

Best Price Found

$163

Fastest flight time

1h 10m

Direct flights

Every day

Airports in St. Louis

1 airport
The best one-way flight to St. Louis from Illinois in the past 72 hours is $163. The best round-trip flight deal from Illinois to St. Louis found on momondo in the last 72 hours is $137.
The fastest flight from Illinois to St. Louis takes 1h 10m
Direct flights go from Illinois to St. Louis every day.
There is 1 airport near St. Louis: Lambert-St Louis (STL)
Search flight deals

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

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

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

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

    The minimum age for a child to fly alone is five, but airlines offering an unaccompanied minor (UNMR) service may have their age restrictions, such as regulations concerning flight duration, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Illinois to Lambert-St Louis Airport.

  • What documentation or ID do you need to fly to Lambert-St Louis Airport?

    The required travel and health documents for your Lambert-St Louis Airport trip may vary depending on your itinerary and personal circumstances. As a general rule, you should carry multiple documents, including a national ID card or driver's license and a passport valid for six months after your intended arrival at Lambert-St Louis Airport. We recommend that you seek guidance from your airline or a reliable third party such as IATA.

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

Best airlines flying from Illinois to St. Louis

Compare and see reviews for airlines that fly from Illinois to St. Louis with momondo
Airline
Rating
Free Cancellation
Price
SouthwestPriceFrom $77Free CancellationRating
8.0
4,241 reviews
Search Southwest flights
Southern / MokulelePriceFrom $118Free CancellationRating
6.5
27 reviews
Search Southern / Mokulele flights
American AirlinesPriceFrom $120Free CancellationRating
7.2
10,000 reviews
Search American Airlines flights
United AirlinesPriceFrom $152Free CancellationRating
7.4
8,941 reviews
Search United Airlines flights

Traveling to a place near St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
St. Charles
Chesterfield
Hermann
Fairview Heights
Maryland Heights
Florissant
O'Fallon
Fenton
Collinsville
Wentzville
Alton
St. Peters
Farmington
Festus
Glencoe
Clayton
Edwardsville
Eureka
Litchfield
Shrewsbury

Why use momondo?

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

It is quick and easy to find Illinois to St. Louis flights on momondo. We search and return numerous flight options from various airlines and agents. You can then use our filters to narrow your search until you have found the most convenient flight to St. Louis that suits you.

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

All flight searches from Illinois to St. Louis on momondo can be filtered to show those which offer flexible booking policies.

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

Once all potential Illinois to St. Louis flight options are in front of you, momondo lets you sort and filter flights based on preferences such as airline, price and flight times amongst many other options.

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

Yes momondo offers price alerts on flights to St. Louis from Illinois. After performing a search on this page you should be able to see the price alert set up feature. Simply provide a valid email address and momondo will instantly alert you when prices change.

An easier way to manage your St. Louis trip

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