$59 Find Cheap Flights from Ontario to Colorado

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Ontario to Colorado departing on 8/4. 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

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

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Ontario to Colorado, 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 Ontario to Colorado, as well as popular online travel agencies
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Best Colorado Flight Deals from Ontario

Cheapest round-trip prices found by our users on KAYAK in the last 72 hours
Denver
Denvernonstop$106
Aspen
Aspen1 stop$299
Grand Junction
Grand Junction1 stop$229
Durango
Durango1 stop$284
Montrose
Montrose1 stop$333
Vail
Vail1 stop$299
Denver
Denvernonstop$106
Aspen
Aspen1 stop$299
Grand Junction
Grand Junction1 stop$229
Durango
Durango1 stop$284
Montrose
Montrose1 stop$333
Vail
Vail1 stop$299

Cheap Flights from Ontario to Colorado

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Ontario to Colorado 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 Ontario to Colorado

Mon, Aug 11 - Thu, Aug 14
Frontier Logo
12:59 am - 4:19 amONT-DEN
2h 20mnonstop
Frontier Logo
10:29 pm - 11:50 pmDEN-ONT
2h 21mnonstop
$106Frontier
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Fri, Jul 25 - Sat, Jul 26
Frontier Logo
12:59 am - 4:19 amONT-DEN
2h 20mnonstop
Frontier Logo
7:49 am - 9:09 amDEN-ONT
2h 20mnonstop
$111Frontier
Find Deal
Wed, Oct 22 - Wed, Oct 29
Southwest Logo
10:45 am - 1:55 pmONT-DEN
2h 10mnonstop
Southwest Logo
8:05 am - 9:25 amDEN-ONT
2h 20mnonstop
$157Southwest
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Sat, Aug 16 - Wed, Aug 20
United Airlines Logo
5:05 am - 8:23 amONT-DEN
2h 18mnonstop
United Airlines Logo
6:08 am - 12:13 pmDEN-ONT
7h 05m1 stop
$167United Airlines
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Sat, Aug 9 - Mon, Aug 11
Southwest Logo
9:15 am - 12:30 pmONT-DEN
2h 15mnonstop
Southwest Logo
5:00 pm - 10:00 pmDEN-ONT
6h 00m1 stop
$177Southwest
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Tue, Nov 4 - Tue, Nov 11
Delta Logo
5:05 pm - 10:29 pmONT-COS
4h 24m1 stop
Delta Logo
5:55 pm - 11:46 pmCOS-ONT
6h 51m1 stop
$217Delta
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Tue, Aug 26 - Tue, Sep 2
Delta Logo
6:05 am - 11:51 amONT-DEN
4h 46m1 stop
Delta Logo
6:25 pm - 10:40 pmDEN-ONT
5h 15m1 stop
$217Delta
Find Deal
Thu, Aug 28 - Tue, Sep 2
United Airlines Logo
6:38 pm - 9:55 pmONT-DEN
2h 17mnonstop
United Airlines Logo
6:08 am - 12:13 pmDEN-ONT
7h 05m1 stop
$237United Airlines
Find Deal
Tue, Aug 5 - Wed, Aug 13
American Airlines Logo
12:55 pm - 6:06 pmONT-DEN
4h 11m1 stop
American Airlines Logo
7:18 am - 11:32 amDEN-ONT
5h 14m1 stop
$249American Airlines
Find Deal
Sat, Aug 2 - Tue, Aug 5
American Airlines Logo
12:55 pm - 11:52 pmONT-COS
9h 57m2 stops
American Airlines Logo
5:00 am - 10:01 amCOS-ONT
6h 01m1 stop
$250American Airlines
Find Deal
Useful Info

KAYAK's insights & trends for Ontario to Colorado flights

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

What is the cheapest Ontario to Colorado flight route?

The cheapest price for flight routes found by users searching on KAYAK in the last 2 weeks for round-trip flights from Ontario to Colorado.

The cheapest ticket to Colorado from Ontario found in the last 72 hours was to Denver, at $116 round-trip. The most popular route is from Ontario (ONT) to Denver (DEN), and the cheapest round-trip airline ticket found on this route in the last 72 hours was $116.

Can I save money by flying with a layover from Ontario to Colorado?

The average round-trip price for all non-stop flights, flights with one layover, and flights with two layovers for the route found by users searching on KAYAK in the last 2 weeks.

Yes, flying with a layover may cost you more time, but you can also save money on the route, with a 1 stop layover the cheapest option at $419 on average.

What is the cheapest month to fly from Ontario to Colorado?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Ontario to Colorado, 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 Ontario to Colorado is January, when tickets cost $98 (return) on average. On the other hand, the most expensive months are June and July, when the average cost of round-trip tickets is $195 and $173 respectively.

What’s the cheapest day of the week to fly from Ontario to Colorado?

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

Your flight ticket price will generally be cheaper if you fly to Colorado on a Saturday and more expensive on a Sunday. On your return trip to Ontario, you should consider flying back on a Saturday, and avoid Sundays for better deals.

How far in advance should I book a flight from Ontario to Colorado?

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Ontario to Colorado, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from Ontario to Colorado, you should book around 2 weeks before departure. For the absolute cheapest price, our data suggests you should book 7 weeks before departure.


Good to know

Low seasonFebruary
High seasonJuly
Cheapest flight$59
Best time to beat the crowds but there is an average 5% increase in price.
Most popular time to fly with an average 1% increase in price.
Flight from Ontario to Denver

FAQs - booking Colorado flights

  • How does KAYAK find such low prices on flights from Ontario to Colorado?

    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 Ontario to Colorado.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight from Ontario to Colorado 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 Ontario to Colorado?

    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 from Ontario to Colorado with an airline and back with another airline.

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

    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 from Ontario to Colorado up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

  • What is the cheapest time of day to fly to Colorado?

    The cheapest time of day to fly to Colorado is generally at night, when round-trip flights cost $195 on average. Morning departures are around 50% more expensive than evening flights, on average. The most expensive time of day to fly to Colorado is generally in the afternoon, which is peak travel time and where the average cost of a ticket is $432.

Top tips for finding cheap flights to Colorado

  • Looking for a cheap flight? 25% of our users found tickets from Ontario to the following destinations at these prices or less: Denver $116 one-way - $210 round-trip

Reviews of the top 5 airlines serving from Ontario to Colorado

 
See real verified KAYAK customer reviews for airlines flying from Ontario to Colorado. 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 Ontario to Colorado? 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 4280 reviews
7.6Entertainment
8.0Comfort
7.1Food
8.2Boarding
8.6Crew
Airline reviews

Southwest is Southwest. No frills. If you're luck enough to get a happy crew (we did), then it makes for a nicer flight.

10.0 ExcellentMichael, Jun 2025SMF - SEA
Read more Southwest reviews

Southwest is Southwest. No frills. If you're luck enough to get a happy crew (we did), then it makes for a nicer flight.

Southwest is typically delayed, and it gets wearisome. It is no longer a discount airline and you get way less than you pay for when it comes to comfort and Ce.

We sat on the plane on the tarmac for 4 hours.

After a 3 hour layover in Denver my flight was delayed over 5 hours! No explanation; no assistance; no offer to provide compensation; no one at Southwest was willing to offer any assistance. 8 hours in the Denver airport - ridiculous!

It was a perfect flight in all aspects! Both legs!

Great flight, 47 passengers on a 180 seat plane. Stewardess was pleasant and cheerful.

I liked the crew member who gave flight instructions on "in case of a problem:. The seats are so small that only a young teenager could sit in middle seat.

WiFi on the flight was not working. Thus, entertainment options were limited.

Great flight staff. Ease of boarding. Overall, very uneventful and easy trip.

I really like open seating. I hate that I've heard this is going away. This is one of the unique things that makes Southwest my goto choice.

Most aspects were good however if they assign boarding zones they ought to enforce them or why bother? My luggage from SAN-JFK-MAD was lost in NY so I without my main bag for two days upon arrival in Spain. They were helpful in tracking it and eventually delivered it to my hotel. The flub was because of a delay upon arrival in NYC. I had booked 2 1/2 hours between flights but we had to hold on the taxiway for an hour after landing while waiting for a clear gate which likely caused the baggage error.

Excellent flight, the planes were newer, they did a nice job with boarding, great service overall.

It would be nice if was given wires ear buds. Overall was a good experience was able to sleep on the plane

My flight was 6 pm 6/6. Every hour they delayed it again - air condition issues then no pilot then the crew had worked too many hours and cancelled the flight at 11 pm. Sent customers to NJ a 45 minutes uber ride to a hotel. Had to be back by 5 am for a 7 am flight and again no pilot etc with another three hours of delays.

737-800 in first class was pretty dumpy. Seat had an uncomfortable angle, storage under the seat was blocked so even my very modest backpack didn't fit, power outlet was flaky. Weird tiny seat pockets that couldn't hold a gallon ziploc bag, emesis bag missing, etc. etc. No in-flight service due to turbulence. Crew was excellent, boarding was smooth despite a full flight.

Delta flight was on time, seats were comfortable, and crew was nice.

Thank you for not flipping the plane on the run way. You guys get a 5 star rating for the flight!!!

Boarding is, as it always is… horrible. Gate lice. Slow moving zones. Too many people with carry ons

It was terrible, if they ran flights on time it would make a big difference.

Delta seems to be improving in many areas, except they are super bad with the food available. Bring back normal food service on long flights.

I was supposed to be on business class at first class from Denver back to Miami due to weather changes. I missed my connection and it’s put on a flight to Fort Lauderdale. Instead of honoring my business class/1st class ticket, they put me in coach, but there were two first class seats open. I think it’s absolutely disgusting that I paid for first class $1300 ticket and they put me in economy and they had to open seats available and I have still not been refunded the difference. I ended up having to eat a snack box instead of the meal I was supposed to get and did not get home till 2 AM so I think that’s a little pathetic that I had to live off crackers for dinner And my poor dog ate some cheese and salami. Oh yes, apparently when they switched me to the new flight they forgot to mention I had a service dog

Excellent service despite turbulence during the flight. Flight attendants were remarkable!

Flight attendant moved my bag without notifying me and was rude to me when I asked him about it. There was no reason to move it.

The gate attendant let me walk right by her with a bag too big for the overhead compartment

Food choices were very limited. Taste of the dishes was average.

I liked all the informational texts. I always knew where to go and when .

Received an email the night before showing that there would be seatback entertainment on our flight. We get on and there was no seatback entertainment. And then it was a scramble to try to set up the iPads for the kids before takeoff so they could watch something for the four hour flight.

The reason I don’t fly United. No in seat entertainment for a long flight and inconsistent WiFi and entertainment available from my device.

It was a good flight. Nothing comes to mind about how it could have been better. It was a newer plane, seemed like a great upgrade from your older ones. Staff was very good as well.

The food for long haul was poor compared to Singapore airlines economy. Pasta plain with tomato sauce . Singapore airlines give me Hagen dash small ice cream cup it was great. The choices of dinner course Singapore air also much better The crew mostly friendly. The economy seat are as expected.

The chair cushions may need an upgrade. I have been noticing they are so worn out, thin so you’d sit in a dip 😄. Other than that, all was an enjoyable trip. Thanks AA!

Cramped seats. FAA should make airlines have more legroom, for even short people complain

Eventless. It was a good flight and good crew. Can’t complaint.

Very helpful ground crew after an earlier flight delay and being rebooked on a different flight.

Terrible. The flight was delayed two hours due to weather. Then when we got on the plane, the first pilot ended up timing out and we had to wait for a second pilot. Second pile came on board and we tax it out. Had to return back to the gate because of an unruly passenger. Then the copilot timed out. Had to wait for new copilot. Also had to wait for maintenance to check for fuel. Then found out the second pilot timed out and we had to wait for a third pilot. Was ready to go and then needed maintenance again for another issue. In the end, it was 2 o’clock in the morning when they announced that the flight couldn’t go because the third pilot and the second copilot had timed out.

The plane was late and then sat on the runway for almost 45 minutes before taking off.

We kept being told that the flight was full and that all overhead compartments were full and therefore had to check in our hand luggage. We were some of the last people to board and noticed that there was still sufficient space in the overhead compartments. We were obliged to check in hand luggage when there was space and so had to wait at luggage retrieval which took a while to then noticed damage to our luggage - not a great experience!

This was an overnight flight. There was no meal service in first class, just a simple snack basket was offered along with beverages. There should have been some type of continental breakfast prior to arrival in PHL. As an Executive Platinum American Airlines Advantage member, I received no name recognition from the first class flight attendant. When disembarking at PHL, the flight attendants were more interested in their cell phones than saying "thank you" to the passengers as they disembarked.

The flight was quick and to the point. The crew just did their job w/o excessive talking and everything was just perfect.

Awkward carry on process. Forced to check all carry on. No overhead space of worthiness. Left delayed, but made up the time. Crew was amicable.

Our flight was cancelled. They could do nothing to help us get another flight that was timely. Because the first leg was cancelled we were unable to get to our connection. We had to book on an entirely different airline for today. So we spent more money, lost a day of vacation and will never fly Frontier again, so the 'we are sorry, here is $100 credit' is a joke since we won't be flying on Frontier.

I liked the turn-style feature at gate 209B at LAX. Very efficient process. The gate staff also made several, clearly directed announcements so I felt very informed.

Seats are uncomfortable but price is good. Guess I can put up with misery for four hours.

The plane failed preflight inspection, so we sat there for 90 mins while they tried to fix it. Ultimately, everything was remedied and we made our connecting flight; instead of a 2 hour layover at the airport, we spent it waiting on the plane.

I loked walking out on the tarmac to board and no first class. I didn't like that they have no snacks or onboard wifi to bide your time.

The seats were extremely hard and uncomfortable. It was disappointing even for a budget airline.

The takeoff was the smoothest I've ever experienced on any airline and this is the first time I've flown on frontier so this was an extremely pleasant surprise!

Delayed each time on a round trip with no significant weather interference. Updates to flight times came after the fact. 30 min behind in boarding and board and phone still show an on time departure. Some mysterious extra 300 miles that came so surprising they had to fuel while we were already on board?

A lady asked to stop the flight after the tunnel pulled away and we began to depart a flight that was already hours late. The attendance respectfully stopped the the plane and had the tunnel return. After the tunnel returned the passenger claimed to have changed her mind . The tunnel was then put in reverse and the passenger remained on the plane .. They should have sent the sick passenger off the plane like initially replaced. They existed a couple off the plane prior to that situation.. So.. all and all.. it was a long and flight.. .

We understand and comply with Frontier’s bag sizes. We’ve had some problems in past while having to await other passengers who do not understand the baggage restrictions or have not prepaid and that is usually our biggest concern (others delaying us) with flying Frontier. Flying OUT of ONT, however, has always been a great experience. I’ve also noted even on delayed Frontier flights very knowledgeable pilots who manage expectations well.

Everything you need to know for your flight from Ontario to Colorado

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