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$184+ Cheap flights from Islip, NY to Ontario (ISP - ONT)

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 5/18. Fares are subject to change and may not be available on all flights or dates of travel.
ISP — ONT
Mar 25 — Apr 11
Wed 3/25
Wed 4/1
1 adult, Economy
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Cheap flight deals from Islip to Ontario

Cheapest flights from Islip to Ontario
Explore the most affordable flight options available from Islip to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on February 23, 2026.

This Southwest deal was found by Cheapflights users on 2/20. 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 3/216:00 am
ISP
-
ONT
1 stop12h 55m
Southwest
Sat 3/289:55 pm
ONT
-
ISP
1 stop10h 50m
Southwest
Deal found 2/20$482
This Southwest deal was found by Cheapflights users on 2/20. 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 3/75:00 am
ISP
-
ONT
2 stops16h 45m
Southwest
Wed 3/119:20 am
ONT
-
ISP
2 stops10h 30m
Southwest
Deal found 2/20$577

Find flight deals from Islip to Ontario

Discover tips and strategies to find the most affordable flight options for your journey from Islip (ISP) to Ontario (ONT). 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 February 23, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$482
(Southwest)

One-way from

$184
(Kiwi.com)

Popular in

December

Cheapest in

January

Average price

$358
Provider with most accurate pricing for Islip Long Island-Ontario flight deals.
Search Deals
Provider most trusted by Cheapflights users for Islip Long Island-Ontario flights.
Search Deals
From Islip Long Island to Ontario
Search Deals
One-way flight from Islip Long Island to Ontario
Search Deals
Highest demand for flights based on searches. 3% potential increase in price ($13 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($9 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in February 2026
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Islip to Ontario 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 February 23, 2026.
Use the filters below to find and compare flights from Islip to Ontario that are best for you.

Fly from

Islip

Fly to

Ontario

Route

Depart

Return

Price

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Sat 3/21

6:00 am-3:55 pm

1 stop12h 55m

Ontario

Sat 3/28

9:55 pm-11:45 am

1 stop10h 50m

$482

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Sat 3/7

5:00 am-6:45 pm

2 stops16h 45m

Ontario

Wed 3/11

9:20 am-10:50 pm

2 stops10h 30m

$577

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Mon 5/18

4:07 pm-6:34 pm

3 stops29h 27m

$197

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Mon 5/18

4:30 pm-11:05 pm

2 stops9h 35m

$202

IslipOntario

ISP - ONT

ISPONT

Islip Long Island

Wed 3/18

4:40 pm-9:40 pm

1 stop8h 00m

$224

Flights are sorted by cheapest round-trip flights first.

Deals found on 2/19

Compare providers for flights from Islip to Ontario

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Islip to Ontario in February.
ProviderPrice AccuracyTrust Score*
FlightHubPrice Accuracy3 starsTrust Score*3 stars
ExpediaPrice Accuracy1 starTrust Score*3 stars

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on Islip, New York-Ontario 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-Ontario flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Islip, New York-Ontario flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Islip, New York-Ontario 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-Ontario 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 Ontario

Have a flexible travel schedule? Discover the best time to fly to Ontario 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.

Cheapflights Insights

Everything you need to know about your flight from Islip to Ontario

What is the cheapest month to book a flight from Islip, New York to Ontario?

Currently, August is the cheapest month in which you can book a flight from Islip, New York to Ontario (average of $90). Flying from Islip, New York to Ontario in February is currently the most expensive (average of $145). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

Related info for your journey

Find useful and relevant information for your journey from Islip to Ontario. 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 Ontario?

    There are many flights that can get you from Islip, New York to Ontario in 12h 55m. Fly via Southwest to get the fastest option. The distance between Islip, New York and Ontario is about 2457 mi.

  • Can I find deals for flights from Islip to Ontario that include hotel bookings?

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

  • How can I find direct flights from Islip to Ontario?

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

  • Can I find deals for business class flights from Islip to Ontario?

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

  • What is the cheapest month to book a flight from Islip, New York to Ontario?

    Currently, August is the cheapest month in which you can book a flight from Islip, New York to Ontario (average of $90). Flying from Islip, New York to Ontario in February is currently the most expensive (average of $145). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

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