DEN - ONT

$43 Find Cheap Flights from Denver to Ontario - 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 Denver to Ontario departing on 7/29. 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

Save 21% or more on flights. Compare deals from all over the web.

Never overpay with our price tracking tools.

Filter searches by price, airline and more to find your best flights.

Everything you should know

Cheapest round-trip
$141
Typical prices: $130-$241
Frontier
Sat 7/25Sat 8/1
DEN - ONT • Non-stop
Cheapest one-way
$43
Typical prices: $100-$213
Frontier
Wed 7/29
DEN - ONT • Non-stop
Advice from real travelers
AI-powered summary based on content written by travel experts. AI can make mistakes.
Frontier Economy Bundle adds a carry-on and seat choice; Premium Bundle adds legroom.
United Economy Plus adds legroom, while Southwest Cash + Points boosts flexibility.
Expert advice
Expert advice
Expert advice
Expert advice
Top airlines
Cheapest • from $141 (round-trip)
Best reviews • 7.9 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
Nonstop flights
Every day
You can fly direct with Frontier, Southwest and United Airlines. Average duration is 2h 20m
Direct flights
Direct flights
+1
+1
Direct flights
Direct flights
+1
When to book
in advance
Our data shows that travelers who book at least 2 weeks in advance save around 24% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
Cheapest • 33% price drop
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
Start a new search
KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to Ontario!
Flight Deals
Booking Insights
Expert advice
Flight Deals

Cheap Flights from Denver to Ontario (DEN-ONT)

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

Sat, Jul 25 - Sat, Aug 1
Frontier Logo
8:45 am - 10:04 am
DEN
-
ONT
2h 19mnonstop
Frontier Logo
6:00 am - 9:24 am
ONT
-
DEN
2h 24mnonstop
$141Frontier
Wed, Oct 14 - Sat, Oct 17
Frontier Logo
10:34 pm - 11:55 pm
DEN
-
ONT
2h 21mnonstop
Frontier Logo
11:38 am - 3:04 pm
ONT
-
DEN
2h 26mnonstop
$143Frontier
Wed, Aug 5 - Wed, Aug 5
Frontier Logo
8:45 am - 10:04 am
DEN
-
ONT
2h 19mnonstop
Frontier Logo
1:38 pm - 9:41 pm
ONT
-
DEN
7h 03m
1 stop
$144Frontier
Wed, Aug 5 - Tue, Aug 11
Frontier Logo
8:45 am - 10:04 am
DEN
-
ONT
2h 19mnonstop
Frontier Logo
8:58 am - 4:21 pm
ONT
-
DEN
6h 23m
1 stop
$147Frontier
Tue, Oct 27 - Tue, Nov 3
Frontier Logo
10:34 pm - 11:55 pm
DEN
-
ONT
2h 21mnonstop
Frontier Logo
2:35 pm - 5:57 pm
ONT
-
DEN
2h 22mnonstop
$148Frontier
Tue, Sep 1 - Wed, Sep 2
Frontier Logo
10:29 pm - 11:50 pm
DEN
-
ONT
2h 21mnonstop
Frontier Logo
3:13 pm - 9:16 pm
ONT
-
DEN
5h 03m
1 stop
$149Frontier
Sat, Nov 14 - Mon, Nov 16
Frontier Logo
12:15 pm - 1:40 pm
DEN
-
ONT
2h 25mnonstop
Frontier Logo
6:15 am - 9:41 am
ONT
-
DEN
2h 26mnonstop
$150Frontier
Wed, Jul 29 - Wed, Jul 29
Frontier Logo
8:45 am - 10:04 am
DEN
-
ONT
2h 19mnonstop
Frontier Logo
1:38 pm - 9:41 pm
ONT
-
DEN
7h 03m
1 stop
$154Frontier
Wed, Jul 29 - Wed, Aug 5
Frontier Logo
10:29 pm - 11:50 pm
DEN
-
ONT
2h 21mnonstop
Frontier Logo
1:38 pm - 9:41 pm
ONT
-
DEN
7h 03m
1 stop
$155Frontier
Sat, Jul 25 - Wed, Jul 29
Frontier Logo
8:45 am - 10:04 am
DEN
-
ONT
2h 19mnonstop
Frontier Logo
6:00 am - 9:24 am
ONT
-
DEN
2h 24mnonstop
$156Frontier
Booking Insights

KAYAK's insights & trends for Denver to Ontario flights

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

How much is a round-trip flight from Denver to Ontario?

This analysis is based on the cheapest round-trip price found on KAYAK in the last 12 months by searching for a flight from Denver to Ontario departing in July.

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

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

When flying from Denver to Ontario, you should consider leaving on a Wednesday and avoid Sundays if you are looking for the best rates. For your return to Denver, you’ll find the best rates on Thursdays and the most expensive ones on Mondays.

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Denver to Ontario, 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 Denver to Ontario is August, where tickets cost $137 (return) on average. On the other hand, the most expensive months are June and March, where the average cost of round-trip tickets is $274 and $261 respectively.

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

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Denver to Ontario, 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 Denver to Ontario, you should book around 2 weeks before departure, which saves you about 24% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 5 weeks before departure.

Expert advice

Expert advice for your flight from Denver to Ontario

 
AI-powered summary based on content written by travel experts. AI can make mistakes.
KAYAK teamed up with top travel experts to share the best tips for your journey.
Our travel experts
Stefanie Waldek

Stefanie Waldek

Expert on Frontier and United Airlines

Stefanie Waldek is a freelance space, travel, and design writer based in Saratoga Springs, NY. Her words have appeared in Space.com, Travel + Leisure, Condé Nast Traveler, Architectural Digest, and House Beautiful, among other publications. An expert in aviation and expedition cruising, Stefanie is frequently up in the air or on the sea, likely en route to Antarctica or the Arctic.

Blane Bachelor

Blane Bachelor

Expert on Southwest

Blane Bachelor is a journalist and editor specializing in travel and aviation who writes regularly for top global outlets. Born and raised in Florida, Blane has worked and lived in four countries, including the Netherlands, where she’s currently based with her family. Her favorite way to get to know a new destination is by running or riding a bike around town – or hearing a spooky ghost story about local history. She will always choose the window seat.

Jennifer Simonson

Jennifer Simonson

Expert on ONT

Jennifer Simonson is driven by her lifelong commitment to exploring the globe. Her insatiable curiosity had led her to immerse herself into diverse locations like Oklahoma City and Pismo. Her hotel recommendations are the result of the myriad hotels she's stayed at across her travels. Along her journey, she cherishes engaging conversations with locals, indulging in the finest ice cream, trying her hand at surfing, and embarking on nature-filled hikes.

Harriet Baskas

Harriet Baskas

Expert on DEN

Harriet is an award-winning journalist who is happiest in an airport or an unusual museum. Her stories about airports, air travel, and the business of travel have appeared on NBC News, CNBC, USA TODAY, The Points Guy and other outlets. She is the creator of the StuckatTheAirport.com blog and the author of nine books. When not out on the road or exploring the latest airport amenities, she’s home in Seattle getting ready for the next adventure.

Good to know

Low seasonJanuary
Cheapest flight$43
Best time to beat the crowds but there is an average 17% increase in price.
Flight from Denver to Ontario

When to book flights from Denver to Ontario

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

  • Where can I find a taxi to travel aboard at ONT?

    Suppose you want to travel from ONT to your destination of choice in Ontario with a taxi. In that case, you can easily find one to travel aboard on the curbside outside the International Arrivals Terminal. As taxis from the airport to ONT travel faster than the public buses that serve this route, traveling aboard a taxi would be wise if you want to travel quickly.

  • Does ONT have on-site restaurants?

    ONT has plenty of restaurants. In this airport's Terminal 2, you can eat at Cross Grain Brewhouse, Harvest & Grounds, and Wolfgang Puck Pizza, while in Terminal 4, you can grab a bite at Coffee Bean & Tea Leaf, Rock & Brews, and Wahoo's Fish Tacos.

  • Where is long-term parking at DEN?

    If you'd like to park your car long-term at DEN, you can do so at three long-term on-site parking options at DEN. They include the East and West Economy Lots, Pikes Peak Lot, and Mt. Elbert Lot. You can count on finding your car intact upon return at any of these lots, as they all boast tight security.

  • Does DEN have a prayer room?

    If you want to pray privately before departing DEN, you'll get the chance to do so, given that DEN is home to a prayer room on the East Side of the Jeppesen Terminal. You'll be allowed to enter this room, irrespective of religion, as it is an interfaith chapel. Since this room is open 24h a day, you can visit it anytime.

  • What is the cheapest flight from Denver to Ontario?

    In the last 5 days, the lowest price for a flight from Denver to Ontario was $43 for a one-way ticket and $141 for a round-trip.

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

    A passport is not required to fly from Denver to Ontario.

  • Which airports will I be using when flying from Denver to Ontario?

    Denver and Ontario are both served by 1 main airport. You will leave Denver from Denver Intl and will be arriving at Ontario.

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

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

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

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

  • Which airline alliances offer flights from Denver to Ontario?

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

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

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

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

    The two airlines most popular with KAYAK users for flights from Denver to Ontario are Southwest and United Airlines. With an average price for the route of $295 and an overall rating of 7.9, Southwest is the most popular choice. United Airlines is also a great choice for the route, with an average price of $295 and an overall rating of 7.4.

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

    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 Denver to Ontario.

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

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

    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 Ontario with an airline and back to Denver with another airline. Booking your flights between Denver and ONT 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 Denver to Ontario?

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

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

  • Looking for a cheap flight? 25% of our users found flights on this route for $124 or less one-way and $183 or less round-trip.
  • To have adequate time to go through Denver International Airport's (DEN) security checkpoints, you should reach the airport at least 2h ahead of your flight. Apart from going through the airport's checkpoints in time for your flight, if you reach the airport as early as advised, you'll get the chance to visit the airport's points of interest.
  • While waiting for your flight to Ontario International Airport (ONT) at DEN, you can relax at American Airlines Admirals Club, United Club, or Delta Sky Club. To enter any of these lounges, you must pay an entrance fee and show that you are traveling with the airline it is affiliated with. Delta Sky Club and American Airlines Admirals Club are found in Concourse A, while United Club has two locations in Concourse B.
  • In case you're traveling with a lactating baby, you can privately breastfeed him/her at DEN. This is because DEN features nursing rooms equipped with comfortable seating, sinks, power outlets, and privacy curtains near the center of Gates A, B, and C.
  • At ONT, you can easily withdraw the money you need before stepping out of the airport, as it features operational ATMs. These ATMs are on the upper and lower levels of Terminals 2 and 4, near the front entrance of the International Terminal, and in the airport's Rental Car Facility.
  • You should head to one of ONT's information desks if you have any inquiries. It's worth noting that you can count on getting fully answered at any of these desks in Terminals 2 and 4, as they feature well-informed airport staff.

Prefer to fly direct from Denver to Ontario?

 
Direct data is based off flight results for the next 60 days. Find direct flights from all airlines flying direct from Denver Intl to Ontario.
Find which airlines fly direct from Denver Intl Airport to Ontario Airport, which days they fly and book direct flights.

Direct departures

Denver Intl to Ontario

Monday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

Tuesday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

Wednesday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

Thursday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

Friday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

Saturday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

Sunday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

See more direct flights

Direct returns

Ontario to Denver Intl

Monday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

Tuesday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

Wednesday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

Thursday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

Friday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

Saturday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

Sunday

Frontier,Southwest,United Airlines

Frontier,Southwest, +1 more

See more direct flights

Reviews of the top 3 airlines serving from Denver to Ontario

 
See real verified KAYAK customer reviews for airlines flying from Denver to Ontario. 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 Denver to Ontario? 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.
7.9
SouthwestOverall score based on 4250 reviews
8.6Crew
7.5Entertainment
8.1Boarding
8.0Comfort
7.0Food
Airline reviews

The flight was late. The crew was rude. There was no food. Cramped and uncomfortable. Nothing about this flight was good.

2.0 MediocreIrene, Jun 2026
DEN - SFO
Read more Southwest reviews

The flight was late. The crew was rude. There was no food. Cramped and uncomfortable. Nothing about this flight was good.

It was just okay, no frills, basic transportation with no luxury. No screens on the seats, no water or drinks on a short flight. Full flight but at least it was on time.

This leg was much better, but we did have to have a 3 hour lay o er after coming from a very exhausting hiccup with our flight from BNA to Den

Connecting flight is on time and boarding was a breeze!

Southwest has a serious issue with keeping their passengers in the dark about delays. They also appear to lack the necessary crews to deal with any sort of hiccup in their operations. The way they run their day-to-day operations is a joke. You are telling me that a hail storm in Denver, where hail storms are incredibly common, results in hours of delays due to every plane needing to be inspected for hail damage? Understandable, but there seems to be a skeleton crew of maintenance workers undergoing this daunting task. There was no particular order of inspecting planes, leading to some planes only having an hour delay or less in others having four or more just because of the luck of the draw of what plane got inspected with no consideration to how long the respective delay was. The entire time the passengers were told nothing except the fact that there was lightning in the area and the ground crews could not load the bags. This always happens that Southwest will incrementally delay a flight with no information given, leaving many frustrated passengers fuming once they find out that their flight is canceled. Don't make people wait around for hours at the airport giving them no information, just to keep them on the hook and prevent any action from being taken by the passengers in terms of finding alternate routes of transportation or accommodations for the night. How many hours of people's times do you think you waste by operating like this? How about having a fully staffed crew in one of your busiest hubs that is famous for severe weather that can effectively deal with a situation like this, or how about having planes on standby to quickly replace in case something like this happens, like all the other major airlines do. This is just like the Christmas fiasco but on a Denver scale, but again this is literally just from a single thunderstorm going over Denver in the spring. I'm glad I've stopped using Southwest as my primary airline and have switched to United. Every single time I fly Southwest, something has to come up. It's ridiculous and I seriously can't wait to finish using my miles so I don't have to deal with your garbage anymore. You used to be so good and I don't know why you thought you could just scrap your quality and expect people to deal with it. Oh, and I walked by someone getting CPR for over 5 minutes in the concourse. I hope he was ok. Southwest needs something similar.

Our flight to Oakland was great bc the plane was new but it was delayed by 15min not bad at all. Over all it was an 8/10

The flight in it self was good. The delays looking for pilots was unexpected.

Flight had over 6 people in wheel chairs and there was only 1 gate agent. Very impressed though in how Maddie handled having to efficiency move that many people by herself. We still nursed in a timely manner.

I loved that the flight was not as full, so we were able to have seats available between us. I just wish wipes are available as we board so that we can clean our areas, as the window area was quite dirty in my case, on both legs of this trip, and it was hard getting the flight attendant's attention for this. She also seemed a bit stingy with the free drinks. I asked for two cups of drinks; she brought one and then waited until I fell asleep and brought the other. Not sure why...

Easy boarding, but no power at the seats and no television wasn’t a good experience.

Destroyed my suitcase. Tired of talking about it. Cancelling my unite mileage plus account.

New plane was lovely. Crew customer service is always lax but expected. Kraft on time and arrived safely.

Wonderful in-seat entertainment with seatback screens and huge selection of quality movies. The ability to bluetooth connect headphones was amazing.

Flight was late - I was downgraded from first class to coach

Great experience…left a bit behind schedule but made up fir that in the air and landed 10 minutes early 😁

See my previous comments. I was probably booked in business but was moved to economy

Generally good but there wasn’t any staff available when my luggage didn’t appear at baggage claim in Fresno. It took about half an hour to locate a staff member to open up the locked room where it was being kept.

Too many fees (but that seems to apply to all airlines nowadays)

United requires seat selection in order for those booking together to stay together.

Serving a coffr Or a Drink would have been nice.

It was awful everything about it terrible I will never ever ever ride it again

The crew was mostly okay. The flight attendant who answered our questions was curt and unhelpful unfortunately. He seemed upset and I understand having off days.

Very bad! No good service delayed my second connection flight

Everything went as planned. Crew was great. Seats were still not that comfortable.

Flight was cancelled and was not able to get another flight thru Frontier. Per frontier a refund was issued but I do not see a refund on my Afirm account.

The agent at check-in was strident, unwelcoming, and condescending to customers ahead of me.

Lost baggage on my connecting flight. 24 hours later, still no update on my bags.

Frontier is a no-frills airlines were the focus is low cost. You get basic service so don't set your expectations high. Watch out thought because this airline, like a few others, will try to nickel and dime you.

Was charged 99 dollars for a bag despite agents previously telling me it would be ok. Customer service was unhelpful

I will like you ( Frontier Airlines) to fly into LAX instead of ONT because I live in LA and the subway takes me to my house in just 15 minutes

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

Information on your arrival and departure airports