$144+ 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 8/7. Fares are subject to change and may not be available on all flights or dates of travel.
ISP — STL
Jul 15 — Jul 221
Round-trip
1 adult, Economy
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Find cheap flights from Islip to St. Louis with Cheapflights
1. Tell us where you want to go
Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”2. Select your favorite providers
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Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.Cheap flight deals from Islip to St. Louis
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Best
Last-minute
One-way
Cheapest flights from Islip to St. LouisExplore 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 June 15, 2026.
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 June 15, 2026.
This Gotogate deal was found by Cheapflights users on 6/12. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/810:57 am
ISP
- STL
1 stop14h 02m
Frontier
Fri 7/104:09 pm
STL
- ISP
1 stop16h 44m
Frontier
Deal found 6/12![Frontier logo]()
$300
This Booking.com deal was found by Cheapflights users on 6/11. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 6/269:52 pm
ISP
- STL
1 stop26h 57m
Frontier
Tue 6/304:17 pm
STL
- ISP
1 stop27h 40m
Frontier
Deal found 6/11![Frontier logo]()
$302
This Southwest deal was found by Cheapflights users on 6/10. 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.
Fri 7/103:05 pm
ISP
- STL
1 stop6h 15m
Southwest
Mon 7/134:30 pm
STL
- ISP
1 stop6h 15m
Southwest
Deal found 6/10![Southwest logo]()
$313
This Southwest deal was found by Cheapflights users on 6/11. 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 7/82:55 pm
ISP
- STL
1 stop5h 20m
Southwest
Sat 7/115:10 am
STL
- ISP
1 stop8h 40m
Southwest
Deal found 6/11![Southwest logo]()
$333
This Southwest deal was found by Cheapflights users on 6/15. 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 10/146:10 am
ISP
- STL
1 stop6h 20m
Southwest
Sat 10/315:40 am
STL
- ISP
1 stop6h 20m
Southwest
Deal found 6/15![Southwest logo]()
$345
This Southwest deal was found by Cheapflights users on 6/12. 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 7/812:25 pm
ISP
- STL
2 stops7h 00m
Southwest
Fri 7/102:50 pm
STL
- ISP
1 stop7h 55m
Southwest
Deal found 6/12![Southwest logo]()
$382
This Southwest deal was found by Cheapflights users on 6/14. 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.
Sun 7/123:30 pm
ISP
- STL
1 stop8h 10m
Southwest
Sat 7/183:45 pm
STL
- ISP
2 stops6h 30m
Southwest
Deal found 6/14![Southwest logo]()
$390
Best flights from Islip to St. LouisDiscover carefully curated flight deals from Islip to St. Louis that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated June 15, 2026.
Discover carefully curated flight deals from Islip to St. Louis that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated June 15, 2026.
This Gotogate deal was found by Cheapflights users on 6/12. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/810:57 am
ISP
- STL
1 stop14h 02m
Frontier
Fri 7/104:09 pm
STL
- ISP
1 stop16h 44m
Frontier
Deal found 6/12![Frontier logo]()
$300
This Southwest deal was found by Cheapflights users on 6/11. 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.
Fri 7/2412:30 pm
ISP
- STL
2 stops7h 00m
Southwest
Fri 7/315:20 pm
STL
- ISP
1 stop5h 20m
Southwest
Deal found 6/11![Southwest logo]()
$318
This Southwest deal was found by Cheapflights users on 6/10. 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.
Fri 7/103:05 pm
ISP
- STL
2 stops6h 45m
Southwest
Mon 7/134:30 pm
STL
- ISP
1 stop6h 15m
Southwest
Deal found 6/10![Southwest logo]()
$318
This Southwest deal was found by Cheapflights users on 6/11. 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 7/86:00 am
ISP
- STL
1 stop6h 30m
Southwest
Sat 7/113:45 pm
STL
- ISP
2 stops6h 30m
Southwest
Deal found 6/11![Southwest logo]()
$333
This Southwest deal was found by Cheapflights users on 6/12. 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 7/812:25 pm
ISP
- STL
2 stops7h 00m
Southwest
Fri 7/102:50 pm
STL
- ISP
1 stop7h 55m
Southwest
Deal found 6/12![Southwest logo]()
$382
This Southwest deal was found by Cheapflights users on 6/14. 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.
Sun 7/123:30 pm
ISP
- STL
1 stop8h 10m
Southwest
Sat 7/183:45 pm
STL
- ISP
2 stops6h 30m
Southwest
Deal found 6/14![Southwest logo]()
$390
Last-minute flights from Islip to St. LouisDiscover last-minute flight deals from Islip to St. Louis. Data last updated June 15, 2026 and is based on user searches.
Discover last-minute flight deals from Islip to St. Louis. Data last updated June 15, 2026 and is based on user searches.
This Booking.com deal was found by Cheapflights users on 6/10. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/159:52 pm
ISP
- STL
1 stop26h 57m
Frontier
Wed 6/174:17 pm
STL
- ISP
1 stop27h 40m
Frontier
Deal found 6/10![Frontier logo]()
$403
This Booking.com deal was found by Cheapflights users on 6/11. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 6/269:52 pm
ISP
- STL
1 stop26h 57m
Frontier
Tue 6/304:17 pm
STL
- ISP
1 stop27h 40m
Frontier
Deal found 6/11![Frontier logo]()
$302
This Southwest deal was found by Cheapflights users on 6/11. 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.
Fri 6/2612:30 pm
ISP
- STL
2 stops7h 00m
Southwest
Tue 6/303:30 pm
STL
- ISP
1 stop6h 05m
Southwest
Deal found 6/11![Southwest logo]()
$439
This Gotogate deal was found by Cheapflights users on 6/12. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/810:57 am
ISP
- STL
1 stop14h 02m
Frontier
Fri 7/104:09 pm
STL
- ISP
1 stop16h 44m
Frontier
Deal found 6/12![Frontier logo]()
$300
This Southwest deal was found by Cheapflights users on 6/11. 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 7/82:55 pm
ISP
- STL
1 stop5h 20m
Southwest
Sat 7/115:10 am
STL
- ISP
1 stop8h 40m
Southwest
Deal found 6/11![Southwest logo]()
$333
This Southwest deal was found by Cheapflights users on 6/12. 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 7/812:25 pm
ISP
- STL
2 stops7h 00m
Southwest
Fri 7/102:50 pm
STL
- ISP
1 stop7h 55m
Southwest
Deal found 6/12![Southwest logo]()
$382
This Southwest deal was found by Cheapflights users on 6/10. 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.
Fri 7/103:05 pm
ISP
- STL
1 stop6h 15m
Southwest
Mon 7/134:30 pm
STL
- ISP
1 stop6h 15m
Southwest
Deal found 6/10![Southwest logo]()
$313
This Southwest deal was found by Cheapflights users on 6/14. 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.
Sun 7/123:30 pm
ISP
- STL
1 stop8h 10m
Southwest
Sat 7/183:45 pm
STL
- ISP
2 stops6h 30m
Southwest
Deal found 6/14![Southwest logo]()
$390
One-way flights from Islip to St. LouisSearch for one-way flight options from Islip to St. Louis. Find affordable one-way fares based on user searches. Data last updated June 15, 2026.
Search for one-way flight options from Islip to St. Louis. Find affordable one-way fares based on user searches. Data last updated June 15, 2026.
This Southwest deal was found by Cheapflights users on 6/11. 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.
Fri 8/712:35 pm
ISP
- STL
1 stop6h 50m
Southwest
Deal found 6/11![Southwest logo]()
$144
This Priceline deal was found by Cheapflights users on 6/10. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/304:41 pm
ISP
- STL
1 stop8h 08m
Frontier
Deal found 6/10![Frontier logo]()
$155
This Southwest deal was found by Cheapflights users on 6/11. 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.
Sat 8/85:30 am
ISP
- STL
2 stops8h 05m
Southwest
Deal found 6/11![Southwest logo]()
$177
This Southwest deal was found by Cheapflights users on 6/10. 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.
Tue 6/302:55 pm
ISP
- STL
2 stops8h 30m
Southwest
Deal found 6/10![Southwest logo]()
$211
This Kiwi.com deal was found by Cheapflights users on 6/11. 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.
Fri 8/71:00 pm
ISP
- STL
3 stops20h 57m
Multiple Airlines
Deal found 6/11![Multiple Airlines logo]()
$249
This Kiwi.com deal was found by Cheapflights users on 6/10. 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 6/305:27 pm
ISP
- STL
3 stops25h 51m
Multiple Airlines
Deal found 6/10![Multiple Airlines logo]()
$350
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 June 15, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $295 (Southwest) |
One-way from | $144 (Southwest) |
Popular in | December |
Cheapest in | August |
Average price | $380 |
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 June 15, 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
Cheapest round-trip
IslipSt. Louis
ISP - STL
ISPSTL
Islip Long Island
Wed 7/8
10:57 am-11:59 pm
1 stop14h 02m
Lambert-St Louis
Fri 7/10
4:09 pm-9:53 am
1 stop16h 44m
$300
Quickest round-trip
IslipSt. Louis
ISP - STL
ISPSTL
Islip Long Island
Fri 7/24
12:30 pm-6:30 pm
2 stops7h 00m
Lambert-St Louis
Fri 7/31
5:20 pm-11:40 pm
1 stop5h 20m
$318
IslipSt. Louis
ISP - STL
ISPSTL
Islip Long Island
Fri 7/10
3:05 pm-8:50 pm
2 stops6h 45m
Lambert-St Louis
Mon 7/13
4:30 pm-11:45 pm
1 stop6h 15m
$318
IslipSt. Louis
ISP - STL
ISPSTL
Islip Long Island
Wed 7/8
6:00 am-11:30 am
1 stop6h 30m
Lambert-St Louis
Sat 7/11
3:45 pm-11:15 pm
2 stops6h 30m
$333
IslipSt. Louis
ISP - STL
ISPSTL
Islip Long Island
Wed 7/8
12:25 pm-6:25 pm
2 stops7h 00m
Lambert-St Louis
Fri 7/10
2:50 pm-11:45 pm
1 stop7h 55m
$382
IslipSt. Louis
ISP - STL
ISPSTL
Islip Long Island
Sun 7/12
3:30 pm-10:40 pm
1 stop8h 10m
Lambert-St Louis
Sat 7/18
3:45 pm-11:15 pm
2 stops6h 30m
$390
Cheapest one-way
IslipSt. Louis
ISP - STL
ISPSTL
Islip Long Island
Fri 8/7
12:35 pm-6:25 pm
1 stop6h 50m
$144
Quickest one-way
IslipSt. Louis
ISP - STL
ISPSTL
Islip Long Island
Sat 8/8
5:30 am-10:50 am
1 stop6h 20m
$189
Sorted by cheapest first
- 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.
ISP-STL
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.
Reviews of airlines servicing St. Louis
Get insights into the airlines that provide service to St. Louis. 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 St. Louis. Reviews last updated June 15, 2026.
Read reviews from past customers who have flown Southwest from Islip to St. Louis. 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.
Entertainment
7.5
Comfort
8.0
Overall
7.9
Food
7.0
Boarding
8.1
Crew
8.6
Reviews
1 / 20
8.0
ExcellentLa Tracimeldamarcos,Jun 2026
LAX - SLC
Entertainment
7.5
Comfort
8.0
Overall
7.9
Food
7.0
Boarding
8.1
Crew
8.6
Reviews
1 / 20
8.0
ExcellentLa Tracimeldamarcos,Jun 2026
LAX - SLC
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.
Traveling to a place near St. Louis?
Book flights to St. Louis if you plan to visit one of these locationsEdwardsville
O'Fallon
Fenton
Swansea
Fairview Heights
Eureka
Maryland Heights
Collinsville
Wentzville
Glencoe
Chesterfield
Alton
Farmington
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Islip and St. Louis flights
Browse other Islip and St. Louis flight options. Last updated on June 15, 2026.
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Browse through other flights departing from Islip. Flights are based on user searches made on Cheapflights and were last updated on June 15, 2026.
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Explore flights to St. Louis departing from other origins. Flights are based on user searches made on Cheapflights and were last updated on June 15, 2026.
Top airline flying from Islip to St. Louis
Discover the top airline that operate flights from Islip to St. Louis. 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 June 15, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$259 | Average$359 | FlexibilityNo cancel fee | On-time63% |