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Find cheap flights from Ontario to Colorado from $39

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 7/4. 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
0 bags
Sun 6/9
Sun 6/16

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Best Colorado Flight Deals

Cheapest round-trip prices found by our users on KAYAK in the last 72 hours

Denver
Denvernonstop$55
Aspen
Aspen1 stop$430
Grand Junction
Grand Junction1 stop$419
Vail
Vail1 stop$430
Durango
Durango1 stop$436
Montrose
Montrose1 stop$341

Good to know

Low season

January

High season

July

Cheapest flight

$39
Best time to beat the crowds with an average 10% drop in price.
Most popular time to fly with an average 9% 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 to Colorado from Ontario 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 to Colorado with an airline and back to Ontario 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 to Colorado from Ontario up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

See more FAQs

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 $84 one-way - $137 round-trip
  • Morning departure is around 14% cheaper than an evening flight, on average*.
*Average of the lowest prices shown in KAYAK’s search results for departures within the next 30 days

Top 5 airlines serving from Ontario to Colorado

 
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.
8.2
China AirlinesOverall score based on 917 reviews
8.3Boarding
8.6Crew
8.0Comfort
8.1Entertainment
7.8Food
Airline reviews

Comfort was left wanting due to such a long flight, made the wife and I wish we could upgrade the seats to Business class or First Class, but did not have that option. Food was good but had very limited options and I have a dietary restriction which was difficult for the staff to accommodate since everything provided came with cheese on it. (Cheese could potentially kill me) Did not have an option to inform the staff until we were already in the air about the restriction and was not provided another option before flight departed.

8.0 ExcellentMichell, Feb 2024TPE - LAX
Read more about China Airlines reviews

Comfort was left wanting due to such a long flight, made the wife and I wish we could upgrade the seats to Business class or First Class, but did not have that option. Food was good but had very limited options and I have a dietary restriction which was difficult for the staff to accommodate since everything provided came with cheese on it. (Cheese could potentially kill me) Did not have an option to inform the staff until we were already in the air about the restriction and was not provided another option before flight departed.

The plane was uncomfortable. I paid extra for more legroom but the seat was still uncomfortable. Other seats on the same exact row didn’t have to pay extra but still have extra legroom. I didn’t understand why I needed to pay $170 for. It was Iike China airline just wants to make money off their passengers. It was unfair.

3 of the 4 flights had delays despite the weather being fine, but still managed to make all connections

Ask flight attendant for water during flight and she was a little rude get the water.

Baggage made it successfully to destination despite short layover. Appreciate that.

Staff were good and nice. There should me 3 meals instead of only 2 and snacks.

Excellent staff made the boarding process fast and easy. Friendly crews on both flights from Saigon to Taipei and Taipei to Los Angeles. Will fly China Airlines again.

For a long-haul flight, the crew did a very good job of keeping the lavatories clean and the aisles clear.

The check-in crew at SF did not put on breakable glass stickers on check-in baggages which caused my antique whisky bottle to break during transportation.

The crews are professional and nice, the flight was on time

I'm a larger, athletic guy (6'2", 260lbs powerlifter) and I found the seats incredibly uncomfortable with minimal leg room, especially in a window seat. Now, I full understand that being smaller may change my view but even if I was 80lbs less, my legs would be the same size and I was sandwiched between my seat and the seat in front of me.

There was a loud squeaky sound the whole time we were flying.

I didn’t not like that I could not select my seat and ended up with the worse seat.

The landing was bad and the hostess came two times and i was sleeping but when she served the person that nexts to me I woke up and she didn’t even asked me if I need any drink or snacks two times!!!!

The helpful attitude of the staff, and being a wheelchair passenger everyone was helpful and understanding. The trip was made comfortable by the upgraded seat which was given without my request, that was a great surprise. Thank you Delta.

Plane was late because of a mechanical malfunction and the food listed as available was not. Flight attendants seem over worked and under paid. They just done seem happy. And that can be seen in their faces.

Waited 3 hours on a plane to de-ice due to manpower issues. Waited another hour and a half once we landed because of a gate issue. Missed my connections. Created. A total of 13 hours of delay.

Great, on time departure, friendly and accommodating crew, great leg room, Smith flight

Plane was turned around due to fog half way into the flight, Delta did not properly direct passengers to stay on same flight and instead failed to properly rebook on Alaska

Like most domestic flights in the US, you are basically on your own with this airline when it comes to food, so be sure to purchase meals and drinks ahead of time or expect to arrive starving and dehydrated (like I was).

I paid $380 for my one-way ticket from California to Minnesota. The fair did not include online check-in. I received instructions from their app to check in at a kiosk. At the kiosk, the boarding pass would not print until an actual person came to verify that I had a personal item and not a carry-on item, On the plane, the person next to me was drunk and allowed to continue to order alcohol. United is garbage I’d rather fly spirit.

The plane was dirty and the in seat air wasn't blowing as planes usually do.

Positive: Entertainment via phone on the short was great and my first time. Good food and wine and head phones for free. Negative: Seat hardly reclined on the long flight. Breakfast was an egg with a bun. No egg choices and rather have something sweet like bun/jam and Youghurt.

They did get us booked on a later flight, but it made us miss our connecting flight. So, we had to stay and another state overnight with no luggage or clothes. Because they kept our luggage at airport for next flight on the next day.

Flight was on time. Staff were friendly. I paid for Economy Plus but was required to check my standard carry-on luggage due to lack of space on the aircraft. This cost me 30 minutes, unexpectedly, in waiting at the baggage claim. This experience did not meet my expectations.

Crew is way too many times on the intercom re explaining the same thing

Amazing comfortable chairs great snacks super friendly staff pilots did excellent job. Smooth sailing all the way. Definitely be flying United more.

We waited too long to get water while the plane was on the Tarmac awaiting de-icing.

Easy peasy. Crew was great. Take-off and landing nice anc chill (good job by the pilot). Thank you UA!

The plane was delayed coming in and on the tarmac. I was coming from another flight so it made for a very long day. The stewardess kept trying to slam the overhead bins closed and I was worried that she had damaged my new luggage. They ran out of snacks and lccdsddd me a hummus box which was nice. It took them a very long time to pick up the garbage so I could not go to the washroom and had little time. To prepare for disbarment. The TV system was hard to control from the armrest and picture wasn’t clear. The crew did apologize several times for the lateness. It took the Denver airport an unusually long time to de-ice the plane.

Horrible - they lied to me about baggage & boarding, even though I specifically spoke to their agents the day before my flight about my issue. When I showed up they did not let me board and stranded me at my airport until I bought a new flight with money I did not have to spend.

The experience was great and much better than the flight going out. of course I was in first class but the service was excellent

Comfort of seats, ease of boarding. Food selection could be better

Food options were limited which is absolutely embarrassing for a Flight of this size The staff did not come around as much and I am not accustomed to such poor service from American Airlines Drinks I believe were limited to soda and water

Because I can’t stand very long in one place, I was allowed to reword.

Crew were attentive and friendly. Flight was smooth and early! I enjoyed the less crowded plane. Thank you!

We are gluten free, there were not any available complimentary gluten free options.

No meal on a cross country flight? SFO-MiA is pretty much the definition of a coast to coast flight. No meal provided. Sky high wi-fi rates too. Stop nickel and diming your customers.

The staff was unprofessional and didn’t communicate very well. The boarding process was very disheveled, potentially due to a power outage the previous day but there was no contingency plan to properly get passengers boarded the following day. Once boarded the aircraft stayed on the tarmac for over 45 minutes due to high winds. The communication was sporadic but an announcement was finally made an additional 30 minutes later that the flight was cancelled but we couldn’t get off the plane. Prior to deplaning one of the gate agents came on the plane and made an announcement for everyone to pickup their checked bags and take a card to rebook a new reservation because they didn’t have adequate staff. Flights were missed, passengers went to different airports and there was little to no assistance from AA.

Apart from the delay due to unforeseen circumstances. The leg from sjc to dfw was fine. It was the leg from dfw to orf that we encountered issues mainly due to the flight attendant crew not being friendly. We had two small children and we needed some assistance to warm up milk so the baby would sleep. The crew just didn’t get it and made things very difficult. One made a remark that the baby’s dirty diaper smell was a “gift” to the plane in a rude way. Normally I’d brush that off as a funny comment if the rest of the trip the attendants were helpful or understanding of the difficulty we faced. But that wasn’t the case. We were met with rudeness on the second leg. Whereas on the first leg the crew were so nice and helpful.

Didn't like anything!! Horrible flight. Small seating area and hard seats. Butt was sore after 2 hour flight to Seattle No entertainment or free refreshments No wifi or USB charging receptacles to charge phone entoute like other airliners Luggage rates were 3 times as much as competitors. Difficult to navigate online luggue process to pre pay before flight Overall bad experience WILL NEVER RIDE OR RECOMMEND FRONTIER TO FRIENDS OR FAMILY MEMBERS!!! THIS IS A SHAME!! MOST MESERIBLE FLIGHT OF MY LIFE!! AND I THOUGHT SPIRIT WAS 👎 YOU GOT THEM BEAD HANDS DOWN!!

There were 3 leg for the trip and each leg was delayed by 90 minutes or more. The boarding process takes forever with people waiting on the jetway even though most folks do not have carry-on. The whole process is poorly managed.

Not have to pay for every single item to take a flight. Seating and delays sucked.

Terrible. Seats are bad and the baggage policy is inconsistent

Flight was delayed on the runway for 40 minutes the crew did not even offer even water to passengers to compensate for the flight delayed. The flight was delayed due to aircraft mechanical issues. Worst customer service ever

Everything was good, and most importantly on time. They have been extremely tardy in some of my flights

They lost my baggage on my connection flight, it’s been 24 hours since I put my claim in and still no update on my bags.

It’s a cheap airline. I wish they had better seats.

The only issues had were outside of Frontier’s control or weren’t expected. It was a two hour flight they completed fast. We landed almost an hour ahead of schedule. The issues with no entertainment or food weren’t issues since there was no expectations. The issue of the loud or crying babies was outside of frontiers control.

Seats are cramped and very uncomfortable. You have to pay for everything and it is too expensive.

Book cheap flights from Ontario to Colorado

Recent round-trip flight deals

7/1Mon
nonstopFrontier
2h 20mONT-DEN
7/4Thu
nonstopFrontier
2h 20mDEN-ONT
$68
7/2Tue
nonstopFrontier
2h 20mONT-DEN
7/9Tue
nonstopFrontier
2h 19mDEN-ONT
$70
6/7Fri
nonstopFrontier
2h 20mONT-DEN
6/12Wed
nonstopFrontier
2h 20mDEN-ONT
$73
6/8Sat
1 stopDelta
4h 54mONT-DEN
6/15Sat
1 stopDelta
6h 06mDEN-ONT
$196
5/21Tue
1 stop
8h 07mONT-DEN
5/25Sat
nonstop
2h 22mDEN-ONT
$202
6/22Sat
1 stopDelta
4h 54mONT-DEN
7/3Wed
1 stopDelta
6h 05mDEN-ONT
$206
8/13Tue
1 stopUnited Airlines
4h 14mONT-COS
8/20Tue
1 stopUnited Airlines
6h 02mCOS-ONT
$272
8/13Tue
2 stopsAmerican Airlines
9h 56mONT-COS
8/20Tue
1 stopAmerican Airlines
6h 00mCOS-ONT
$277
8/13Tue
2 stopsAmerican Airlines
9h 56mONT-COS
8/20Tue
2 stopsAmerican Airlines
11h 08mCOS-ONT
$282
6/11Tue
1 stopUnited Airlines
4h 28mONT-COS
7/10Wed
1 stopUnited Airlines
4h 40mCOS-ONT
$304

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Recent one-way flight deals

7/4Thu
nonstopFrontier
2h 21mONT-DEN
$39
8/9Fri
nonstopFrontier
2h 21mONT-DEN
$41
6/1Sat
1 stopDelta
5h 22mONT-DEN
$98
7/31Wed
1 stopAmerican Airlines
4h 06mONT-DEN
$109
8/8Thu
1 stopAmerican Airlines
4h 10mONT-DEN
$114
5/25Sat
1 stopDelta
4h 56mONT-DEN
$118
6/15Sat
nonstopUnited Airlines
2h 17mONT-DEN
$119
6/1Sat
1 stopUnited Airlines
7h 41mONT-DEN
$128
5/18Sat
1 stopAlaska Airlines
7h 00mONT-DEN
$148
8/13Tue
2 stopsAlaska Airlines
15h 58mONT-DEN
$182

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Last minute flights from Ontario to Colorado

Last minute flight, train and bus deals

5/14Tue
nonstopFrontier
2h 24mONT-DEN
5/21Tue
nonstopFrontier
2h 22mDEN-ONT
$109
5/14Tue
nonstopFrontier
2h 24mONT-DEN
5/22Wed
nonstopFrontier
2h 24mDEN-ONT
$117
5/14Tue
multi-stopDelta
8h 10mONT-DEN
5/15Wed
multi-stopDelta
6h 33mDEN-ONT
$296
5/13Mon
multi-stopUnited Airlines
25h 44mONT-DEN
5/14Tue
nonstopUnited Airlines
2h 23mDEN-ONT
$545
5/14Tue
multi-stopUnited Airlines
25h 44mONT-DEN
5/15Wed
nonstopUnited Airlines
2h 23mDEN-ONT
$557
5/13Mon
multi-stopAlaska Airlines
26h 37mONT-DEN
5/18Sat
multi-stopAlaska Airlines
9h 21mDEN-ONT
$569
5/14Tue
multi-stopAlaska Airlines
26h 29mONT-DEN
5/16Thu
multi-stopAlaska Airlines
8h 51mDEN-ONT
$589
5/12Sun
multi-stopAmerican Airlines
3h 43mONT-DEN
5/15Wed
multi-stopAmerican Airlines
4h 42mDEN-ONT
$682
5/13Mon
multi-stopAmerican Airlines
9h 53mONT-COS
5/20Mon
multi-stopAmerican Airlines
8h 52mCOS-ONT
$699
5/10Fri
multi-stopDelta
11h 43mONT-COS
5/14Tue
multi-stopDelta
10h 42mCOS-ONT
$2,580

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Ontario - Colorado Flights

Departure:

Ontario (ONT)United States

Return flight deals:

Colorado - Ontario

Cabin classes:

$438
$845
$410
$70