$128+ Cheap flights from Islip, NY to St. Louis (ISP - STL)
This is the cheapest round-trip flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 11/11. Fares are subject to change and may not be available on all flights or dates of travel.
ISP — STL
Oct 12 — Oct 191
Round-trip
1 adult, Economy
We work with more than 300 partners to bring you better travel deals
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
We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.3. Compare prices and book
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
Cheapest
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 September 12, 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 September 12, 2026.
This Southwest deal was found by Cheapflights users on 9/9. 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 10/25:40 pm -
1 stop6h 35m
Tue 10/63:20 pm -
1 stop6h 20m
Deal found 9/9![Southwest logo]()
$265
This CheapOair deal was found by Cheapflights users on 9/9. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/105:43 pm -
1 stop23h 51m
Sun 9/135:19 pm -
1 stop22h 39m
Deal found 9/9![Frontier logo]()
$340
This Southwest deal was found by Cheapflights users on 9/9. 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 10/93:10 pm -
1 stop9h 10m
Tue 10/133:20 pm -
1 stop6h 20m
Deal found 9/9![Southwest logo]()
$366
This Southwest deal was found by Cheapflights users on 9/7. 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 9/223:20 pm -
1 stop6h 55m
Sat 9/266:45 am -
1 stop6h 45m
Deal found 9/7![Southwest logo]()
$421
This Southwest deal was found by Cheapflights users on 9/10. 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.
Sat 9/263:15 pm -
1 stop6h 30m
Wed 9/301:40 pm -
1 stop6h 30m
Deal found 9/10![Southwest logo]()
$464
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 September 12, 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 September 12, 2026.
This Southwest deal was found by Cheapflights users on 9/9. 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 10/25:40 pm -
1 stop6h 35m
Tue 10/63:20 pm -
1 stop6h 20m
Deal found 9/9![Southwest logo]()
$265
This Southwest deal was found by Cheapflights users on 9/9. 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 10/93:10 pm -
1 stop9h 10m
Tue 10/135:25 am -
2 stops9h 05m
Deal found 9/9![Southwest logo]()
$372
This Frontier deal was found by Cheapflights users on 9/8. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 1/2511:59 am -
1 stop13h 05m
Sun 1/315:59 pm -
2 stops16h 05m
Deal found 9/8![Frontier logo]()
$784
This Southwest deal was found by Cheapflights users on 9/7. 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 9/223:20 pm -
1 stop6h 55m
Sat 9/266:45 am -
1 stop6h 45m
Deal found 9/7![Southwest logo]()
$421
This Southwest deal was found by Cheapflights users on 9/10. 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.
Sat 9/263:15 pm -
1 stop6h 30m
Wed 9/301:40 pm -
1 stop6h 30m
Deal found 9/10![Southwest logo]()
$464
Last-minute flights from Islip to St. LouisDiscover last-minute flight deals from Islip to St. Louis. Data last updated September 12, 2026 and is based on user searches.
Discover last-minute flight deals from Islip to St. Louis. Data last updated September 12, 2026 and is based on user searches.
This CheapOair deal was found by Cheapflights users on 9/9. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/125:43 pm -
1 stop23h 51m
Mon 9/145:19 pm -
1 stop22h 39m
Deal found 9/9![Frontier logo]()
$340
This Southwest deal was found by Cheapflights users on 9/7. 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 9/223:20 pm -
1 stop6h 55m
Sat 9/266:45 am -
1 stop6h 45m
Deal found 9/7![Southwest logo]()
$421
This Southwest deal was found by Cheapflights users on 9/10. 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.
Sat 9/263:15 pm -
1 stop6h 30m
Wed 9/301:40 pm -
1 stop6h 30m
Deal found 9/10![Southwest logo]()
$464
This Southwest deal was found by Cheapflights users on 9/9. 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 10/25:40 pm -
1 stop6h 35m
Tue 10/63:20 pm -
1 stop6h 20m
Deal found 9/9![Southwest logo]()
$265
This Southwest deal was found by Cheapflights users on 9/9. 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 10/93:10 pm -
1 stop9h 10m
Tue 10/133:20 pm -
1 stop6h 20m
Deal found 9/9![Southwest logo]()
$366
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 September 12, 2026.
Search for one-way flight options from Islip to St. Louis. Find affordable one-way fares based on user searches. Data last updated September 12, 2026.
This Southwest deal was found by Cheapflights users on 9/9. 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 11/114:05 pm -
1 stop7h 05m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/9![Southwest logo]()
$128
This Kiwi.com deal was found by Cheapflights users on 9/9. 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 11/1112:00 pm -
3 stops36h 16m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/9![Multiple Airlines logo]()
$179
This Frontier deal was found by Cheapflights users on 9/10. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/166:55 pm -
2 stops25h 02m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/10![Frontier logo]()
$427
This Frontier deal was found by Cheapflights users on 9/10. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/96:55 pm -
2 stops25h 02m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/10![Frontier logo]()
$478
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 September 12, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $265 (Southwest) |
One-way from | $128 (Southwest) |
Popular in | July |
Cheapest in | January |
Average price | $370 |
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 7,457,451 searches. Data last updated September 12, 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
Quickest round-trip
IslipSt. Louis
ISP Islip Long Island - STL Lambert-St Louis
ISPSTL
Islip Long Island
Wed 11/11
4:05 pm-10:10 pm
1 stop7h 05m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$128
IslipSt. Louis
ISP Islip Long Island - STL Lambert-St Louis
ISPSTL
Islip Long Island
Wed 11/11
12:00 pm-11:16 pm
3 stops36h 16m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$179
IslipSt. Louis
ISP Islip Long Island - STL Lambert-St Louis
ISPSTL
Islip Long Island
Fri 10/2
5:40 pm-11:15 pm
1 stop6h 35m
Lambert-St Louis
Tue 10/6
3:20 pm-10:40 pm
1 stop6h 20m
$265
IslipSt. Louis
ISP Islip Long Island - STL Lambert-St Louis
ISPSTL
Islip Long Island
Fri 10/9
3:10 pm-11:20 pm
1 stop9h 10m
Lambert-St Louis
Tue 10/13
5:25 am-3:30 pm
2 stops9h 05m
$372
IslipSt. Louis
ISP Islip Long Island - STL Lambert-St Louis
ISPSTL
Islip Long Island
Tue 9/22
3:20 pm-9:15 pm
1 stop6h 55m
Lambert-St Louis
Sat 9/26
6:45 am-2:30 pm
1 stop6h 45m
$421
IslipSt. Louis
ISP Islip Long Island - STL Lambert-St Louis
ISPSTL
Islip Long Island
Fri 10/16
6:55 pm-6:57 pm
2 stops25h 02m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$427
IslipSt. Louis
ISP Islip Long Island - STL Lambert-St Louis
ISPSTL
Islip Long Island
Sat 9/26
3:15 pm-8:45 pm
1 stop6h 30m
Lambert-St Louis
Wed 9/30
1:40 pm-9:10 pm
1 stop6h 30m
$464
IslipSt. Louis
ISP Islip Long Island - STL Lambert-St Louis
ISPSTL
Islip Long Island
Fri 10/9
6:55 pm-6:57 pm
2 stops25h 02m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$478
IslipSt. Louis
ISP Islip Long Island - STL Lambert-St Louis
ISPSTL
Islip Long Island
Mon 1/25
11:59 am-12:04 am
1 stop13h 05m
Lambert-St Louis
Sun 1/31
5:59 pm-11:04 am
2 stops16h 05m
$784
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 September 12, 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
Overall
8.0
Boarding
8.1
Food
7.0
Crew
8.6
Comfort
8.0
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Entertainment
7.5
Overall
8.0
Boarding
8.1
Food
7.0
Crew
8.6
Comfort
8.0
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
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 locationsFairview Heights
O'Fallon
Fenton
Swansea
Eureka
Maryland Heights
Collinsville
Wentzville
Edwardsville
Glencoe
Chesterfield
Browse thousands of different options on Cheapflights for your next trip
Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.
Alternative routes
Complete your trip
Flights by cabin class
Other flight options
Other flights from Islip
Popular flights
St. Louis flight routes
Alternative routes for Islip to St. Louis
See prices for flight routes from nearby airports that may be better suited for you.
Complete your trip
Complete your trip to St. Louis by adding a car rental and/or hotel reservation to your travel itinerary.
Search flights from Islip to St. Louis by cabin class
Find flights from Islip to St. Louis, based on your preferred cabin class, be it economy, premium economy, business, or first class.
Islip and St. Louis flights
Browse other Islip and St. Louis flight options. Last updated on September 12, 2026.
Other flights from Islip
Browse through other flights departing from Islip. Flights are based on user searches made on Cheapflights and were last updated on September 12, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Other flights to St. Louis
Explore flights to St. Louis departing from other origins. Flights are based on user searches made on Cheapflights and were last updated on September 12, 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 7,457,451 searches. Data last updated September 12, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$214 | Average$288 | FlexibilityNo cancel fee | On-time63% |