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$111+ Cheap flights from Islip, NY to St. Louis (ISP - STL)

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 5/4. Fares are subject to change and may not be available on all flights or dates of travel.
ISP — STL
May 29 — Jun 51
Fri 5/29
Fri 6/5
1 adult, Economy
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Cheap flight deals from Islip to St. Louis

Cheapest flights from Islip to St. Louis
Explore the most affordable flight options available from Islip to St. Louis. Find the lowest fares from popular airlines and budget airlines, with prices last updated on April 29, 2026.

This Expedia deal was found by Cheapflights users on 4/28. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/266:02 pm
ISP
-
STL
1 stop6h 55m
Frontier
Tue 6/24:19 pm
STL
-
ISP
1 stop16h 46m
Frontier
Deal found 4/28$160
This Kiwi.com deal was found by Cheapflights users on 4/28. 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.
Thu 5/2811:00 am
ISP
-
STL
1 stop13h 57m
Frontier
Mon 6/84:19 pm
STL
-
ISP
1 stop22h 37m
Frontier
Deal found 4/28$243
This Kiwi.com deal was found by Cheapflights users on 4/27. 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 5/2711:00 am
ISP
-
STL
2 stops31h 33m
Frontier
Wed 6/34:19 pm
STL
-
ISP
1 stop16h 46m
Frontier
Deal found 4/27$262
This Trip.com deal was found by Cheapflights users on 4/25. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 6/511:00 am
ISP
-
STL
1 stop13h 57m
Frontier
Sun 6/74:19 pm
STL
-
ISP
1 stop16h 46m
Frontier
Deal found 4/25$302
This Southwest deal was found by Cheapflights users on 4/24. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/276:55 am
ISP
-
STL
2 stops7h 30m
Southwest
Wed 6/32:10 pm
STL
-
ISP
2 stops7h 30m
Southwest
Deal found 4/24$328

Find flight deals from Islip to St. Louis

Discover tips and strategies to find the most affordable flight options for your journey from Islip (ISP) to St. Louis (STL). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated April 29, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$160
(Expedia)

One-way from

$111
(Frontier)

Popular in

November

Cheapest in

August

Average price

$388
Provider with most accurate pricing for Islip Long Island-Lambert-St Louis flight deals.
Search Deals
Provider most trusted by Cheapflights users for Islip Long Island-Lambert-St Louis flights.
Search Deals
From Islip Long Island to Lambert-St Louis
Search Deals
One-way flight from Islip Long Island to Lambert-St Louis
Search Deals
Highest demand for flights based on searches. 7% potential increase in price ($28 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 1% potential price decrease ($4 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in April 2026
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Islip 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, Cheapflights users made 2,558,603 searches. Data last updated April 29, 2026.
Use the filters below to find and compare flights from Islip to St. Louis that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 5/27

11:00 am-11:57 pm

1 stop13h 57m

Lambert-St Louis

Wed 6/3

4:19 pm-10:05 am

1 stop16h 46m

$268

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Wed 5/27

6:55 am-1:25 pm

2 stops7h 30m

Lambert-St Louis

Wed 6/3

2:10 pm-10:40 pm

2 stops7h 30m

$328
Quickest round-trip

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 6/8

6:05 pm-12:05 am

1 stop7h 00m

Lambert-St Louis

Thu 6/11

4:25 pm-11:35 pm

2 stops6h 10m

$349

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Fri 9/11

12:35 pm-6:25 pm

1 stop6h 50m

Lambert-St Louis

Sun 9/13

7:40 am-3:55 pm

1 stop7h 15m

$360

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Thu 9/10

1:15 pm-10:25 pm

2 stops10h 10m

Lambert-St Louis

Sun 9/13

7:40 am-3:55 pm

1 stop7h 15m

$365

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Sat 7/11

2:45 pm-10:00 pm

1 stop8h 15m

Lambert-St Louis

Mon 7/13

5:20 pm-11:35 pm

1 stop5h 15m

$375

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Tue 5/26

4:10 pm-10:10 pm

2 stops7h 00m

Lambert-St Louis

Tue 6/2

2:30 pm-10:10 pm

2 stops6h 40m

$380

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Sat 8/1

5:15 pm-11:25 pm

1 stop7h 10m

Lambert-St Louis

Sat 8/15

5:15 am-2:30 pm

2 stops8h 15m

$382

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Sun 5/10

6:05 am-11:05 am

1 stop6h 00m

Lambert-St Louis

Thu 5/14

2:20 pm-10:30 pm

1 stop7h 10m

$411
Cheapest one-way

IslipSt. Louis

ISP - STL

ISPSTL

Islip Long Island

Mon 5/4

4:07 pm-11:19 pm

1 stop8h 12m

$111

Flights are sorted by cheapest round-trip flights first.

Deals found on 4/25

Showing 1-10 of 14 resultsSorted by cheapest first
1
2
  • Most accurate provider: When it comes to deals on Islip, New York-St. Louis flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Islip, New York-St. Louis flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Islip, New York-St. Louis flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Islip, New York-St. Louis flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Islip, New York-St. Louis flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

Best time to book a flight from Islip to St. Louis

Have a flexible travel schedule? Discover the best time to fly to St. Louis from Islip 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.

Related info for your journey

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

  • How long is the flight from Islip, New York to St. Louis?

    Airlines like Frontier and Southwest fly from Islip, New York to St. Louis in about 7h 30m. The time it takes to get you to your destination can typically vary by up to 6h 27m. Islip, New York and St. Louis are separated by a distance of 926 mi. This flight may include one or multiple stops.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Islip to St. Louis by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

See more FAQs

Traveling to a place near St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
Edwardsville
O'Fallon
Fenton
Swansea
Fairview Heights
Maryland Heights
Collinsville
Eureka
Wentzville
Glencoe
Chesterfield
Alton
Farmington
Festus

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