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$81+ Cheap flights from Islip, NY to Denver (ISP - DEN)

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 3/2. Fares are subject to change and may not be available on all flights or dates of travel.
ISP — DEN
Jan 11 — Jan 181
Sun 1/11
Sun 1/18
1 adult, Economy
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Cheap flight deals from Islip to Denver

Cheapest flights from Islip to Denver
Explore the most affordable flight options available from Islip to Denver. Find the lowest fares from popular airlines and budget airlines, with prices last updated on December 12, 2025.

This CheapOair deal was found by Cheapflights users on 12/10. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/218:35 pmISP - DEN
1 stop28h 29mFrontier
Mon 12/2911:59 pmDEN - ISP
1 stop22h 00mFrontier
Deal found 12/10$259
This CheapOair deal was found by Cheapflights users on 12/11. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/186:00 amISP - DEN
1 stop10h 54mFrontier
Thu 12/256:00 amDEN - ISP
1 stop15h 31mFrontier
Deal found 12/11$285
This CheapOair deal was found by Cheapflights users on 12/10. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/186:00 amISP - DEN
1 stop10h 54mFrontier
Sun 12/2111:59 pmDEN - ISP
1 stop17h 41mFrontier
Deal found 12/10$289
This CheapOair deal was found by Cheapflights users on 12/11. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/206:00 amISP - DEN
1 stop28h 56mFrontier
Mon 12/226:00 amDEN - ISP
1 stop15h 59mFrontier
Deal found 12/11$305
This CheapOair deal was found by Cheapflights users on 12/10. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/316:00 amISP - DEN
1 stop28h 56mFrontier
Wed 1/711:59 pmDEN - ISP
1 stop17h 46mFrontier
Deal found 12/10$313
This CheapOair deal was found by Cheapflights users on 12/10. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/126:00 amISP - DEN
1 stop11h 43mFrontier
Mon 12/157:00 amDEN - ISP
1 stop14h 59mFrontier
Deal found 12/10$334
This CheapOair deal was found by Cheapflights users on 12/9. 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.
Fri 12/198:35 pmISP - DEN
1 stop28h 29mFrontier
Fri 12/266:00 amDEN - ISP
1 stop15h 59mFrontier
Deal found 12/9$338
This CheapOair deal was found by Cheapflights users on 12/10. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/111:15 pmISP - DEN
1 stop28h 28mFrontier
Sun 12/1411:00 pmDEN - ISP
1 stop22h 59mFrontier
Deal found 12/10$339
This CheapOair deal was found by Cheapflights users on 12/11. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/1310:19 amISP - DEN
1 stop14h 45mFrontier
Sat 12/2011:59 pmDEN - ISP
1 stop22h 00mFrontier
Deal found 12/11$364
This CheapOair deal was found by Cheapflights users on 12/9. 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.
Sun 12/1412:07 pmISP - DEN
1 stop23h 03mFrontier
Sun 12/2111:59 pmDEN - ISP
1 stop22h 00mFrontier
Deal found 12/9$368
This CheapOair deal was found by Cheapflights users on 12/11. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/298:35 pmISP - DEN
1 stop22h 41mFrontier
Sat 1/176:59 pmDEN - ISP
1 stop11h 56mFrontier
Deal found 12/11$382
This CheapOair deal was found by Cheapflights users on 12/10. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/218:35 pmISP - DEN
1 stop28h 29mFrontier
Mon 1/59:24 amDEN - ISP
1 stop8h 15mFrontier
Deal found 12/10$388

Find flight deals from Islip to Denver

Discover tips and strategies to find the most affordable flight options for your journey from Islip (ISP) to Denver (DEN). 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 December 12, 2025.

Most accurate provider

eDreams
3 stars

Most trusted provider

eDreams
3 stars

Round-trip from

$183
(CheapOair)

One-way from

$81
(CheapOair)

Popular in

December

Cheapest in

September

Average price

$653
Provider with most accurate pricing for Islip Long Island-Denver Intl flight deals.
Search Deals
Provider most trusted by Cheapflights users for Islip Long Island-Denver Intl flights.
Search Deals
From Islip Long Island to Denver Intl
Search Deals
One-way flight from Islip Long Island to Denver Intl
Search Deals
Highest demand for flights based on searches. 4% potential increase in price ($24 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($15 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Islip to Denver 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 December 12, 2025.
Use the filters below to find and compare flights from Islip to Denver that are best for you.

Fly from

Islip

Fly to

Denver

Route

Depart

Return

Price

IslipDenver

ISP - DEN

ISPDEN

Islip Long Island

Thu 1/8

8:40 pm-8:24 am

1 stop13h 44m

Denver Intl

Mon 1/12

11:59 pm-10:46 pm

1 stop20h 47m

$183

IslipDenver

ISP - DEN

ISPDEN

Islip Long Island

Tue 1/13

8:00 am-11:23 am

1 stop29h 23m

Denver Intl

Wed 1/21

11:20 am-6:48 pm

1 stop29h 28m

$183

IslipDenver

ISP - DEN

ISPDEN

Islip Long Island

Mon 1/26

7:43 pm-9:35 am

1 stop15h 52m

Denver Intl

Tue 2/10

11:25 am-1:13 pm

1 stop23h 48m

$204

IslipDenver

ISP - DEN

ISPDEN

Islip Long Island

Fri 2/6

2:31 pm-9:49 pm

1 stop9h 18m

Denver Intl

Mon 2/9

10:29 pm-1:13 pm

2 stops36h 44m

$221

IslipDenver

ISP - DEN

ISPDEN

Islip Long Island

Mon 1/5

8:24 pm-10:59 pm

1 stop28h 35m

Denver Intl

Fri 1/9

11:59 pm-7:08 pm

1 stop17h 09m

$239

IslipDenver

ISP - DEN

ISPDEN

Islip Long Island

Sun 1/11

8:40 pm-8:24 am

1 stop13h 44m

Denver Intl

Wed 1/14

10:22 am-12:57 pm

1 stop24h 35m

$239

IslipDenver

ISP - DEN

ISPDEN

Islip Long Island

Wed 1/14

8:00 am-8:20 am

1 stop26h 20m

Denver Intl

Sun 2/1

5:01 pm-6:48 pm

1 stop23h 47m

$283

IslipDenver

ISP - DEN

ISPDEN

Islip Long Island

Tue 12/23

6:25 am-8:56 am

1 stop28h 31m

Denver Intl

Thu 1/1

6:00 am-11:31 pm

1 stop15h 31m

$305

IslipDenver

ISP - DEN

ISPDEN

Islip Long Island

Thu 3/5

10:42 am-11:04 pm

1 stop14h 22m

Denver Intl

Thu 3/12

8:45 am-7:11 pm

1 stop8h 26m

$312

IslipDenver

ISP - DEN

ISPDEN

Islip Long Island

Mon 1/5

2:04 pm-11:04 pm

1 stop11h 00m

Denver Intl

Thu 1/8

9:44 am-7:45 pm

1 stop8h 01m

$312

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/10

Showing 1-10 of 21 results
1
2
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Compare providers for flights from Islip to Denver

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 Denver in December.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy2 starsTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*1 star
eDreamsPrice Accuracy3 starsTrust Score*3 stars
PricelinePrice 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-Denver flights, users find the pricing of eDreams to be most consistent on Cheapflights vs. eDreams Users can find the same prices on Islip, New York-Denver flight deals on Cheapflights vs. eDreams >95% of the time. Price accuracy is based on data collected from Islip, New York-Denver flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Islip, New York-Denver flights, Cheapflights users trust eDreams the most. eDreams 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-Denver 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 Denver

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

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

Currently, October is the cheapest month in which you can book a flight from Islip, New York to Denver (average of $88). Flying from Islip, New York to Denver in May is currently the most expensive (average of $143). 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.

What is the cheapest time of day to fly from ISP to DEN?

Find hourly flight availability from Islip to Denver. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated December 12, 2025.

It’s typically best to fly out from Islip, New York to Denver in the evening. Doing so could potentially save you 68% on the flight price compared to flying at noon, which is usually more expensive.

How much does it cost to fly round-trip from Islip, New York to Denver?

Reviews of airlines servicing Denver

Get insights into the airlines that provide service to Denver. 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 Denver. Reviews last updated December 12, 2025.
Peruse reviews from past customers who have flown with Southwest and Frontier from Islip to Denver to help guide your decision. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
7.9
Good
4,252 reviews

Food

7.0

Comfort

8.0

Crew

8.6

Entertainment

7.5

Boarding

8.1

Overall

7.9

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Southwest
7.9
Good
4,252 reviews
Southwest
7.9
Good
4,252 reviews

Food

7.0

Comfort

8.0

Crew

8.6

Entertainment

7.5

Boarding

8.1

Overall

7.9

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Frontier
5.8
Fair
3,084 reviews
Southwest
7.9
Good
4,252 reviews

Food

7.0

Comfort

8.0

Crew

8.6

Entertainment

7.5

Boarding

8.1

Overall

7.9

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

Related info for your journey

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

    Frontier can get you from Islip, New York to Denver in just under 13h 44m. Your travel time can differ by up to . The distance between Islip, New York and Denver is about 1654 mi.

  • What are the cheapest airlines flying from Islip, New York to Denver round-trip?

    Frontier, at $144, was found to be the cheapest airline from Islip, New York to Denver. An alternate airline flying to your destination would be Southwest. These flights start at 70% lower than the current average price 3 months from now.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Islip to Denver 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 Denver?

    Currently, October is the cheapest month in which you can book a flight from Islip, New York to Denver (average of $88). Flying from Islip, New York to Denver in May is currently the most expensive (average of $143). 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.

See more FAQs

Traveling to a place near Denver?

Book flights to Denver if you plan to visit one of these locations
Black Hawk
Thornton
Westminster
Broomfield
Lakewood
Golden
Winter Park
Greeley
Lone Tree
Cripple Creek
Silverthorne
Central City
Frisco
Wheat Ridge
Manitou Springs
Fort Morgan
Brighton
Longmont
Idaho Springs
Parker

Browse thousands of different options on Cheapflights for your next trip

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Alternative routes for Islip to Denver

See prices for flight routes from nearby airports that may be better suited for you.
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Top 2 airlines flying from Islip to Denver

Discover the top 2 airlines that operate flights from Islip to Denver. 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 December 12, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$190Average$260FlexibilityNo cancel feeOn-time62%
SouthwestCheapest$377Average$521FlexibilityNo cancel feeOn-time63%

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