ISP - DEN

$71 Find Cheap Flights from Islip to Denver

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 12/10. 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

KAYAK searches hundreds of travel sites at once for deals on flights to Denver

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Islip to Denver, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Islip to Denver, as well as popular online travel agencies
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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

Tue, Nov 11 - Thu, Nov 13
Frontier Logo
11:30 am - 9:58 amISP-DEN
24h 28m1 stop
Frontier Logo
6:00 am - 8:54 amDEN-ISP
24h 54m1 stop
$130Frontier
Find Deal
Thu, Dec 4 - Sun, Dec 7
Frontier Logo
1:15 pm - 3:43 pmISP-DEN
28h 28m1 stop
Frontier Logo
11:59 pm - 9:13 amDEN-ISP
7h 14m1 stop
$137Frontier
Find Deal
Tue, Nov 11 - Thu, Nov 13
Frontier Logo
6:27 pm - 11:16 pmISP-DEN
30h 49m1 stop
Frontier Logo
6:00 am - 8:54 amDEN-ISP
24h 54m1 stop
$142Frontier
Find Deal
Wed, Nov 12 - Tue, Nov 18
Frontier Logo
4:58 pm - 11:16 pmISP-DEN
8h 18m1 stop
Frontier Logo
12:16 am - 10:37 amDEN-ISP
8h 21m1 stop
$150Frontier
Find Deal
Mon, Nov 10 - Wed, Nov 12
Frontier Logo
9:54 am - 9:58 amISP-DEN
26h 04m1 stop
Frontier Logo
2:00 pm - 9:09 amDEN-ISP
17h 09m1 stop
$176Frontier
Find Deal
Wed, Nov 12 - Sun, Nov 16
Frontier Logo
4:58 pm - 11:16 pmISP-DEN
8h 18m1 stop
Frontier Logo
11:59 pm - 9:09 amDEN-ISP
7h 10m1 stop
$182Frontier
Find Deal
Fri, Nov 14 - Sun, Nov 16
Frontier Logo
9:39 am - 9:08 amISP-DEN
25h 29m1 stop
Frontier Logo
12:16 am - 10:37 amDEN-ISP
8h 21m1 stop
$183Frontier
Find Deal
Wed, Nov 12 - Tue, Nov 18
Frontier Logo
4:58 pm - 8:01 pmISP-DEN
29h 03m2 stops
Frontier Logo
12:16 am - 10:37 amDEN-ISP
8h 21m1 stop
$195Frontier
Find Deal
Wed, Nov 12 - Wed, Nov 19
Multiple Airlines Logo
4:58 pm - 8:15 amISP-DEN
17h 17m1 stop
Multiple Airlines Logo
9:07 am - 9:07 amDEN-ISP
22h 00m2 stops
$264Multiple Airlines
Find Deal
Fri, Nov 14 - Mon, Nov 17
Multiple Airlines Logo
2:25 pm - 7:26 pmISP-DEN
7h 01m1 stop
Multiple Airlines Logo
9:00 am - 5:42 pmDEN-ISP
30h 42m1 stop
$377Multiple Airlines
Find Deal

Everything you should know

When to travel
September
Cheapest • 29% price drop
May
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
Cheapest round-trip
$130
Typical prices: $253-$462
Frontier
Tue 11/11Thu 11/13
ISP - DEN • 1 stop
Cheapest one-way
$71
Frontier
Wed 12/10
ISP - DEN • 1 stop
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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!
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 November.

What’s the cheapest day of the week to fly from Islip to Denver?

The average price of all round-trip flights from Islip to Denver clicked on KAYAK for each day over the last 12 months.

Your flight ticket price will generally be cheaper if you fly to Denver on a Wednesday and more expensive on a Friday. On your return trip to Islip, you should consider flying back on a Thursday, and avoid Wednesdays for better deals.

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 September, where tickets cost $336 (return) on average. On the other hand, the most expensive months are April and March, where the average cost of round-trip tickets is $631 and $611 respectively.

Good to know

Low seasonJanuary
Cheapest flight$71
Best time to beat the crowds with an average 2% drop in price.
Most popular time to fly with an average 11% increase in price.
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 3 days, the lowest price for a flight from Islip to Denver was $71 for a one-way ticket and $130 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.

  • Which is the best airline for flights from Islip to Denver, Southwest or Frontier?

    The two airlines most popular with KAYAK users for flights from Islip to Denver are Southwest and Frontier. With an average price for the route of $521 and an overall rating of 8.0, Southwest is the most popular choice. Frontier is also a great choice for the route, with an average price of $217 and an overall rating of 5.8.

  • 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 airlines 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 4242 reviews
8.1Boarding
8.6Crew
7.0Food
8.0Comfort
7.5Entertainment
Airline reviews

Ever since Southwest starting charging for bags, passengers don't want to pay to check their bags, so the gate agents have to beg people to check their roller bags now because there's "not enough space". This was a terrible business move by Southwest.

8.0 ExcellentGreg, Oct 2025OAK - BUR
Read more Southwest reviews

Ever since Southwest starting charging for bags, passengers don't want to pay to check their bags, so the gate agents have to beg people to check their roller bags now because there's "not enough space". This was a terrible business move by Southwest.

Full cans of soda would be nice. A choice between two snacks would be appreciated.

Tried watching free movie and it kept freezing so I couldn’t finish.

All was good. I just had a hard time getting connected to the WiFi/internet during the flight

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

Great flight. Outstanding Service. Southwest was able to put us on a direct flight to Denver when the connection could have been affected by a later arrival to Baltimore. The direct flight was less expensive that the flight with the connection in Baltimore.

Delays delays delays. Late taking off, late landing, wait for a gate, etc.

Flight was delayed due to plane not passing inspection And one of the crew had to time out and we had to wait for another one A 3 hour delay

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...

I knew going into this that Frontier, being a low cost carrier, would be pretty bare bones and charge for most extras but this was made up for by the fact that the airplane was a reasonably new Airbus, every employee was great and best of all, Everett Washington is an amazing airport - thanks Frontier for flying there!!!

Seats were new and comfortable. Staff was fine. Missed my connection due to weather -which wasn’t their fault- but got no help at all. Gate staff sent me to customer service, which was and stayed unstaffed. Sign with QR code directed me to call or chat. Chat was useless. Call was returned after an hour. No itinerary offered by Frontier could get me home in less than 30 hours. Rebooked with another airline and got a partial refund that came to about 10 percent of what I paid to get home.

The experience was good. No frills but I got there safe and sound and on time.

As every law enforcement agency I could imagine surrounded the plane and we didn’t disembark for 2 hours and then had to stick around for another hour to go get our personal belongings after leaving them behind and being bused away from the plane, it was scary and inconvenient. We were given no information as to why this was happening. Lack of communication with passengers was disappointing.

Frontier Airlines was AWFUL. I was an hour early for my flight and the lady refused to check me in. I had to purchase a whole new ticket with a different airline.

Late, terrible communication, horrible planning of passenger seating until the literal last minute. One of the worst flying experiences of my life. Y'all suck

First of all, we never got on the connecting flight to Denver. They delayed our flight for two hours. If we would have gotten on that flight, we would have been stuck in Denver for 13 hours. So we re- routed our flight for a straight through flight to Oklahoma two days later. THEN, they delayed that flight for two hours. After that we were able to finally get on our flight and come home. Frontier Airlines - one of the worst airlines I have ever been on.

Terrible communication with weather delay, lost baggage, near impossible to reach customer service

My tickets got canceled on me by your site and I didn't have a flight. Then you kept sending me emails on the status of q flight I didn't have tickets for.

Flight was late. Missed connecting in Denver. My new flight is more than 24 hours later and I have no room, vouchers, or compensation, and might also be bumped from the one tomorrow.

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

Information on your arrival and departure airports

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