ISP - DEN

$131 Find Cheap Flights from Islip to Denver - Compare and Save

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Islip to Denver departing on 8/24. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

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Everything you should know

Cheapest round-trip
$250
Typical prices: $345-$528
Frontier
Mon 8/31Thu 9/3
ISP - DEN • 1 stop
Cheapest one-way
$131
Frontier
Mon 8/24
ISP - DEN • 1 stop
Top airlines
Cheapest • from $250 (round-trip)
Best reviews • 8.0 score
Airline reviews
Airline reviews
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Airline reviews
Airline reviews
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Nonstop flights
Not available
There are currently no direct flights between Islip and Denver. You'll need at least 1 connection.
Insights
Insights
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Insights
Top layover airports
Cheapest • Avg $190 (round-trip)
Shortest trip • 6h 41m (one-way)
Insights
Insights
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Insights
When to travel
Cheapest • 100% price drop
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
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KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to Denver!
Flight Deals
Booking Insights
Flight Deals

Cheap Flights from Islip to Denver (ISP-DEN)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Islip to Denver that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Islip to Denver

Mon, Aug 31 - Thu, Sep 3
Frontier Logo
7:09 pm - 8:07 am
ISP
-
DEN
14h 58m
1 stop
Frontier Logo
6:00 am - 6:14 pm
DEN
-
ISP
10h 14m
1 stop
$250Frontier
Thu, Sep 3 - Wed, Sep 9
Frontier Logo
7:09 pm - 7:33 am
ISP
-
DEN
14h 24m
1 stop
Frontier Logo
6:40 am - 4:58 pm
DEN
-
ISP
8h 18m
1 stop
$250Frontier
Thu, Sep 3 - Wed, Sep 9
Frontier Logo
7:09 pm - 7:33 am
ISP
-
DEN
14h 24m
1 stop
Frontier Logo
6:40 am - 4:58 pm
DEN
-
ISP
8h 18m
1 stop
$250Frontier
Thu, Aug 20 - Tue, Aug 25
Frontier Logo
7:09 pm - 7:33 am
ISP
-
DEN
14h 24m
1 stop
Frontier Logo
11:59 pm - 9:53 am
DEN
-
ISP
7h 54m
1 stop
$250Frontier
Mon, Aug 24 - Mon, Aug 31
Frontier Logo
7:46 pm - 11:07 pm
ISP
-
DEN
29h 21m
1 stop
Frontier Logo
6:00 am - 7:01 pm
DEN
-
ISP
11h 01m
1 stop
$250Frontier
Sat, Oct 10 - Tue, Oct 13
Frontier Logo
8:55 pm - 7:32 am
ISP
-
DEN
12h 37m
1 stop
Frontier Logo
11:59 pm - 3:03 pm
DEN
-
ISP
13h 04m
1 stop
$250Frontier
Thu, Aug 27 - Mon, Aug 31
Frontier Logo
7:09 pm - 7:33 am
ISP
-
DEN
14h 24m
1 stop
Frontier Logo
11:59 pm - 9:53 am
DEN
-
ISP
7h 54m
1 stop
$250Frontier
Thu, Sep 10 - Mon, Sep 14
Southwest Logo
6:45 am - 2:35 pm
ISP
-
DEN
9h 50m
1 stop
Southwest Logo
5:15 am - 12:35 pm
DEN
-
ISP
5h 20m
1 stop
$369Southwest
Tue, Sep 22 - Tue, Sep 29
Southwest Logo
12:55 pm - 7:45 pm
ISP
-
DEN
8h 50m
2 stops
Southwest Logo
6:00 am - 5:00 pm
DEN
-
ISP
9h 00m
2 stops
$379Southwest
Thu, Aug 20 - Tue, Aug 25
Southwest Logo
6:10 am - 10:05 am
ISP
-
DEN
5h 55m
1 stop
Southwest Logo
9:35 am - 9:05 pm
DEN
-
ISP
9h 30m
2 stops
$385Southwest
Booking Insights

KAYAK's insights & trends for Islip to Denver flights

Get data-powered insights and trends into flights from Islip to Denver to help you find the cheapest flights, the best time to fly and much more.

How much is a round-trip flight from Islip, New York to Denver?

This analysis is based on the cheapest round-trip price found on KAYAK in the last 12 months by searching for a flight from Islip, New York to Denver departing in September.

Flight prices are below average for this route right now.

Flights to Denver from Islip, New York usually cost between $472 and $644 in September.
The lowest price found in the past 5 days was $250 on Frontier (Sep 3-Sep 9).

What is the cheapest month to fly from Islip to Denver?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Islip to Denver, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Islip to Denver is January, where tickets cost $0 (return) on average. On the other hand, the most expensive months are April and December, where the average cost of round-trip tickets is $942 and $653 respectively.

Good to know

Low season

September

Cheapest flight

$131
Best time to beat the crowds with an average 29% drop in price.
Most popular time to fly and prices are also 2% lower on average.
Flight from Islip to Denver

When to book flights from Islip to Denver

Are your dates flexible? Find out the best times to travel from Islip to Denver based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking flights from Islip to Denver

  • What is the cheapest flight from Islip to Denver?

    In the last 5 days, the lowest price for a flight from Islip to Denver was $131 for a one-way ticket and $250 for a round-trip.

  • Do I need a passport to fly between Islip and Denver?

    No

  • Which aircraft models fly most regularly from Islip to Denver?

    We unfortunately don’t have that data for this specific route.

  • How does KAYAK find such low prices on flights from Islip to Denver?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Islip to Denver.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Islip to Denver?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Denver from Islip is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Islip to Denver?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to Denver with an airline and back to Islip with another airline. Booking your flights between Islip and DEN can sometimes prove cheaper using this method.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Islip to Denver?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to Denver from Islip up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

Reviews of the top airline flying from Islip to Denver

 
See real verified KAYAK customer reviews for airlines flying from Islip to Denver. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Islip to Denver? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
SouthwestOverall score based on 4229 reviews
8.6Crew
8.0Comfort
8.1Boarding
7.0Food
7.5Entertainment
Airline reviews

Friendly crew kept coming by to make sure all was ok, provide additional refreshments, etc.

10.0 ExcellentTamara, Jul 2026
MCO - DEN
Read more Southwest reviews

Friendly crew kept coming by to make sure all was ok, provide additional refreshments, etc.

Flight was delayed by 2 hours, meaning that a flight to Dwnver which should have arrived at 11pm came into the airport at 1 am. Made for a very long day.

Crew was rude, flight was late, wifi didn't work, no food, basically nothing about this flight was good.

Airline is not very senior friendly. Flights are late, forcing us to run to the connecting flight. Food is awful. Wish they would go back to pretzels and peanuts. During flight, pressurization isn’t quite right and all of our ears get plugged. Everything is nickel and dime, charging for boarding, seat selection and legroom. While a screen at the desk in the gate area says check your roll on bag now for free due to space limitation, the employee at the desk will not check the bag without a $100 fee. Insane.

We waited in the airplane for over 45 min for a southwest employee to make the flight. This cause over half the plane to miss their connecting flight in Denver. When we confronted the desk upon arrival, they told us the only flight they had was the next day leaving at 8:50 pm!!! Or they offered to get us to Burbank or LA, but after that we were on our own to get back to Santa Barbara. I paid for a flight from sba to bna bna to sba. My re entry into mom mode has been 💯 rough because of southwest mistake with my flight. And now I’m leaving to Reno tomorrow for a vballl tournament and just discovered that my leg in Vegas has me and my 3 kids on a stand by flight even though I had booked these ticket last year November!! Do better southwest!

I appreciate the staff who allowed me to board though I arrived a little late! Regarding the assigned seating, I had booked my flight before this change and wasn't aware of the change at the time, and so I didn't select a seat at booking as I didn't realize it was relevant. Better communication about the change would have been helpful for preparing.

Sacrament staff are always polite and helpful. Airport is easy to maneuver and boarding is straightforward.

Near 4 hour flight with only 1 service. Had to use call button to request water. Internet and power not working until into flight. Internet would stop working during flight.

The Southwest employees (all two of them) were very nice and cheerful despite the fact the line to self-check a bag (simply drop it off) was hundreds of people long. Thank God I arrived early to the airport because I stood in this line for at least an hour. Once on the flight that had been delayed by an hour, we had no Wi-Fi and thus no entertainment. Finally, I hope the investor strong arm tactics against Southwest pay off in a short-term windfall to your C-Suite because the rest of you are screwed. I have been a faithful Southwest customer for 15 years due to everything you just got rid of. I'm flying to Idaho and Washington in October, both places I used to simply book with Southwest without a second thought now with Frontier (Washington) and United (Idaho) because they offer everything the "new" Southwest does but cheaper and at better times, destinations, etc. This really makes me sad...

Flights delayed by 4-6 hours. Boarding was a mess and unclear. Bags were not at arrival airport and had never even been put on the plane. No idea when I’ll get them. Don’t fly into Denver!

Everything you need to know for your flight from Islip to Denver

Information on your arrival and departure airports