ONT - DEN

$24 Find Cheap Flights from Ontario 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 Ontario to Denver departing on 2/25. 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.
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These are the airlines KAYAK users have selected most often from within our search results in flight searches from Ontario 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 Ontario to Denver, as well as popular online travel agencies
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Cheap Flight Deals from Ontario to Denver Intl (ONT-DEN)

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

Recent round-trip flight deals from Ontario to Denver

Recommended round-trip deals departing in the coming months from the most popular airlines that fly from Ontario to Denver.
Discover the best prices and deals for you by selecting your travel dates.
Choose your dates
12:59 am - 4:16 amONT-DEN
2h 17mnonstop
10:34 pm - 12:06 amDEN-ONT
2h 32mnonstop
$48Frontier
Find Deal
Mon, Feb 24 - Wed, Feb 26
12:59 am - 4:16 amONT-DEN
2h 17mnonstop
10:27 pm - 11:59 pmDEN-ONT
2h 32mnonstop
$53Frontier
Find Deal
Fri, Feb 21 - Tue, Feb 25
7:45 am - 11:10 amONT-DEN
2h 25mnonstop
10:34 pm - 12:06 amDEN-ONT
2h 32mnonstop
$57Frontier
Find Deal
Wed, Feb 5 - Wed, Feb 12
6:00 am - 4:12 pmONT-DEN
9h 12m1 stop
10:34 pm - 12:06 amDEN-ONT
2h 32mnonstop
Tue, Feb 25 - Wed, Feb 26
6:00 am - 4:12 pmONT-DEN
9h 12m1 stop
10:37 pm - 12:09 amDEN-ONT
2h 32mnonstop
Tue, Feb 25 - Fri, Feb 28
5:45 am - 9:00 amONT-DEN
2h 15mnonstop
9:35 am - 11:05 amDEN-ONT
2h 30mnonstop
$157Southwest
Find Deal
Tue, Feb 25 - Wed, Feb 26
4:30 pm - 7:40 pmONT-DEN
2h 10mnonstop
10:25 pm - 11:55 pmDEN-ONT
2h 30mnonstop
$177Southwest
Find Deal
Sat, Feb 22 - Thu, Feb 27
1:44 pm - 5:03 pmONT-DEN
2h 19mnonstop
7:25 pm - 8:52 pmDEN-ONT
2h 27mnonstop
$212United Airlines
Find Deal
Sat, Feb 22 - Sat, Feb 22
5:05 am - 8:24 amONT-DEN
2h 19mnonstop
11:15 am - 12:42 pmDEN-ONT
2h 27mnonstop
$217United Airlines
Find Deal
Sat, Feb 22 - Tue, Feb 25
6:00 am - 1:03 pmONT-DEN
6h 03m1 stop
8:16 am - 12:29 pmDEN-ONT
5h 13m1 stop
$237Delta
Find Deal
Sat, Mar 22 - Thu, Mar 27

Flights from Ontario to Denver - Travel Insights & Trends

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

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

The average price of all round-trip flights from Ontario 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 Saturday and more expensive on a Sunday. On your return trip to Ontario, you should consider flying back on a Tuesday, and avoid Sundays for better deals.

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Ontario 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 Ontario to Denver is January, where tickets cost $128 (return) on average. On the other hand, the most expensive months are March and August, where the average cost of round-trip tickets is $171 and $171 respectively.

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

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.
No, with an average price for the route of $768, prices are generally cheapest when you fly direct.

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

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 Denver, 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 Denver, you should book around 2 weeks before departure. For the absolute cheapest price, our data suggests you should book 4 weeks before departure.

Good to know

Low season

January

High season

July

Cheapest flight

$24
Best time to beat the crowds with an average 15% drop in price.
Most popular time to fly with an average 3% increase in price.
Flight from Ontario to Denver

When to book flights from Ontario to Denver

Are your dates flexible? Find out the best times to travel from Ontario 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 Ontario to Denver

  • What are the transit options at Denver International Airport (DEN)?

    There is a large network of transit options that connect to Denver International Airport (DEN). You can use the airport rail serving the eight stations which runs regularly every 15min during the day and every 30min at night. Also, you can opt for ground transportation such as hotel shuttles, taxis, ride shares, and rental car shuttles. However, if you are in a hurry, the most convenient option is to use a taxi.

  • Can I exchange my foreign currency at Denver International Airport (DEN)?

    Denver International Airport (DEN) has three global money exchange locations. They are located in Gates A, B, and Jeppesen Terminal Level 5. You can also use the airport exchange kiosk, although they have the worst exchange rates.

  • What transportation option is available to Ontario Airport (ONT)?

    There are many ways you can get to Ontario Airport (ONT) from Ontario City Center. Public transits offer cheap and easy travel although takes longer to arrive at the airport. The station is right within ONT for easy passenger access. There is also the use of airport shuttles to provide transportation to passengers. Alternatively, you can use a taxi, which is the fastest way to get to the airport.

  • Are there nursing suites at Denver International Airport (DEN)?

    There are various options of nursing suites for passengers with kids at Denver International Airport (DEN). They are located at each of DEN’s concourses, offering excellent security and a peaceful environment to nurse after a long flight. Also, the suites are available throughout the day and night.

  • What is the cheapest flight from Ontario to Denver?

    In the last 3 days, the lowest price for a flight from Ontario to Denver was $24 for a one-way ticket and $48 for a round-trip.

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

    No

  • Which airlines offer Wi-Fi service onboard planes from Ontario to Denver?

    Delta, Alaska Airlines, American Airlines, and JetBlue offer inflight Wi-Fi service on the Ontario to Denver flight route.

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

    The Airbus A320neo is the aircraft model that flies most regularly on the Ontario to Denver flight route.

  • Which airline alliances offer flights from Ontario to Denver?

    Star Alliance is the only airline alliance operating flights between Ontario and Denver.

  • On which days can I fly direct from Ontario to Denver?

    There are nonstop flights from Ontario to Denver on a daily basis.

  • Which is the best airline for flights from Ontario to Denver, Southwest or Delta?

    The two airlines most popular with KAYAK users for flights from Ontario to Denver are Southwest and Delta. With an average price for the route of $254 and an overall rating of 8.1, Southwest is the most popular choice. Delta is also a great choice for the route, with an average price of $232 and an overall rating of 8.0.

  • How does KAYAK find such low prices on flights from Ontario 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 Ontario to Denver.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Denver 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 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 Ontario with another airline. Booking your flights between Ontario 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 Ontario 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 Ontario up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

See more FAQs

KAYAK’s top tips for finding a cheap flight from Ontario to Denver

  • Looking for a cheap flight? 25% of our users found flights on this route for $91 or less one-way and $136 or less round-trip.
  • If you are flying out of Ontario Airport (ONT) and need to park, you will find various parking spots. There are long and short-term parking options depending on how long you want to park. The parking stalls are open throughout to every passenger who wishes to park offering the ultimate convenience. They are located in each terminal providing valet, premium, and general parking options.
  • When flying from Ontario Airport (ONT), it is recommended that you arrive at least 2h earlier before your scheduled flight. It is vital to consider the time you will take when checking in at the airport, getting boarding passes, and passing through security checks. Luckily, the Ontario Airport (ONT) waiting time is improving to excellent staffing and screening options.
  • There are multiple power stations in all terminals when you get to Denver International Airport (DEN) and need to work. The stations are well-equipped making it comfortable to work at your convenience.
  • With multiple lounges at Denver International Airport (DEN), passengers can take advantage of the services and refuel when waiting for the next flight or shuttle bus. All the lounges are easily accessible as they are located near passenger departures.
  • If you are having an early morning flight and looking for accommodation, there are various hotels near Ontario Airport (ONT) offering excellent services like free shuttle transfer to the airport. These hotels include Double Tree by Hilton Hotel located 0.9 miles from the airport and Holiday Inn Ontario Airport, which is around 0.7 miles from the airport.
See more tips

Prefer to fly direct from Ontario to Denver?

Find which airlines fly direct from Ontario Airport to Denver Intl Airport, which days they fly and book direct flights.

Direct departures

Ontario to Denver Intl

Monday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

Tuesday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

Wednesday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

Thursday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

Friday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

Saturday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

Sunday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

See more direct flights

Direct returns

Denver Intl to Ontario

Monday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

Tuesday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

Wednesday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

Thursday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

Friday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

Saturday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

Sunday

Air Canada, Frontier, Southwest, +1 more

Air Canada, Frontier, +2 more

See more direct flights
See more direct flights

Top 4 airlines serving from Ontario to Denver

 
See real verified KAYAK customer reviews for airlines flying from Ontario 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 Ontario 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.
8.1
SouthwestOverall score based on 4647 reviews
8.1Comfort
7.2Food
7.7Entertainment
8.7Crew
8.2Boarding
Airline reviews

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.

8.0 ExcellentGavin, Jan 2025SEA - DEN
Read more Southwest reviews

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.

Employees were kind and funny, as always! Flight was late but no announcements were made for people with tight connections to help them transition quickly. No service due to turbulence.

I recently flew Southwest from San Jose to Honolulu. I was very impressed with the flight crew, especially the flight attendant in charge of the front of the plane. She came through the aisle at least five times for drinks and water, and two times for snacks. I have not seen such service since I flew first class. Also, for the first time, they gave us the correct baggage claim number, and the luggage came out quickly. I can't wait for Southwest to have assigned seating! I absolutely hate the Cattle Call boarding procedure and the mad dash to get seats and overhead bins. However, the boarding was efficient.

For the first time in a long time we had a flawless experience with Southwest. Both flights were early and no mechanical errors at all. We were shocked and pleasantly surprised 😮.

One of the crew performed a hilarious skit to accompany the standard instructions. Passengers enjoyed it so much they applauded at the end!

We had a nice flight. Boarding was easy, our seats were comfortable and the on board service was pleasant.

It was really nice! I appreciate the gate attendant allowing families with small children to board early on in the process… that was very helpful! The internet service didn’t work with the app I was trying to use even though I paid the $8… other than that it was great! Oh and I should’ve asked for the whole cranberry cocktail can. That cup was about 2 sips…

A bit expensive for the overall service; but the flight departed on time and arrived early.

I love no assigned seats and bags fly free. If Private Equity gets their way and forces Southwest to change they will be everyone else and I will stop being loyal to them. DON'T CHANGE YOUR BUSINESS MODEL!!!

Crew always seems to be unprofessional no matter what Southwest flight I fly

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.

Airline lost my luggage and set me back a day worth of travel due to having to stay in Denver to wait on my luggage

I actually received a notification from kayak on email but not one by text from Delta when my departure gait changed and I almost missed my flight

New boarding doesn't make sense. Filling front first is slow.

Delta flight was great from the check in all the way to arrival. However, I had a very bad experience. I requested a wheelchair and the wheelchair employee that went to pick me up from the plane in Boston to bring me to the baggage claims told me I have to pay him. I was under the impression that it was a free service and I usually give tips but the person forced me to pay and since I said no because I was upset with his demand when my daughter walked in to pick me up he demanded payment from my daughter who paid him thinking maybe now it is a charged service.

Horrible. Grateful to be alive but spent 13 hours at airport only to return back to my familys house and flight changed to next day. They tried to fix a part on plane, had no back up plane and after 10 hours , reattempted the flight and it STILL wasn't fixed. We got a meal voucher and rescheduled flight but there should be some other compensation for the 15 hours spent in airport

My seat was changed at the last minute and I was moved to the last row, right next to the bathroom despite selecting my seat well in advance. I was also made to check my carry on due to space but when I got on the plane there was significant empty overhead space. Picking up my carry on from the luggage carousel added time to my trip which had already been extended due to delay.

There was plenty of overhead room but half of the passengers were told they had to check their carryon bags. My partner and I checked in as early as possible and our seats were split across the aisle.

Flew first class so everything was great. But maybe because the flights were red eye, no meals were served, just chips. I flew Alaska Air 1st class at 9PM (2 hour flight) and they served beef short rib sliders!

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 plane was clean. The staff was excellent. The flight attendants were very good. Enjoyable flight. Overall. The seats in the back are too small but, will always be.

Flight was 3 1/2 hour delayed with no credit or meal vouchers

late departure due to some unspecified issue with ventilating the cabin. They got it running but it was FREEZING for the whole flight. I asked for a blanket but they didn't provide one. They could not turn up the heat. it was quite miserable.

Liked that we left on time for each flight. Snacks not the best, but we're okay.

It was fine. The flight attendant appeared to be in a bad mood but everything was fine.

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.

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?

Our flight was canceled for no known reason. We weren’t told until we were checking in at 5:00 am. This was after our last flight with Frontier where we sat on the plane for three hours (not an exaggeration) before we took off because of a mechanical issue. We won’t be flying Frontier again.

Allowed me to chose my seat without extra charge (I purchased full-price ticket) and boarding was in group1. Didn't even serve water.

Stuck in Phoenix for two days, not even a hotel voucher offered.

Every day about it was very different all the boarding pass where all wrong l miss flight no refund all crazy

Flight got delayed for 3.5 hours, and for the first hour after the departure time there was no update from the gate folks...

Both flights were delayed. The sizing of bags is crazy. I know it is advertised as a no frills cheaper option but it does feel like you are being extorted for money the whole way-- $20 dollars to talk to a gate agent? Charging for soda a pretzels? I don't think I will be flying Frontier again if I can help it. That said, all the staff were wonderful.

Staff members pretty horrible when boarding. No care for customers

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

Information on your arrival and departure airports

Compare transportation modes for Ontario to Denver

Average priceAverage duration
Flights$7832h 10m
Buses$26921h 00m

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