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Ontario

$23+ Cheap flights from Denver to Ontario (DEN - ONT)

DEN — ONT
Sep 20 — Sep 271
Sun 9/20
Sun 9/27
1 adult, Economy
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Find cheap flights from Denver to Ontario with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.
Cheapflights Tip: The best prices from Denver Intl to Ontario are usually found in May or April, booked 84 days in advance, depart on a Saturday or Tuesday and return on a Friday

Cheap flight deals from Denver to Ontario

Cheapest flights from Denver to Ontario

Tue 10/209:01 am -
Nonstop2h 28m
Wed 10/216:15 am -
Nonstop2h 26m
Deal found 8/19$66
Thu 9/249:05 am -
Nonstop2h 25m
Mon 9/286:15 am -
Nonstop2h 20m
Deal found 8/18$67
Thu 10/110:29 pm -
Nonstop2h 18m
Wed 10/711:45 am -
Nonstop2h 22m
Deal found 8/18$68
Tue 10/139:01 am -
Nonstop2h 28m
Sat 10/176:15 am -
Nonstop2h 26m
Deal found 8/17$71
Tue 9/88:45 am -
Nonstop2h 19m
Thu 9/1011:45 am -
Nonstop2h 22m
Deal found 8/17$72
Fri 9/119:05 am -
Nonstop2h 25m
Tue 9/1511:45 am -
Nonstop2h 22m
Deal found 8/17$74
Fri 10/169:01 am -
Nonstop2h 28m
Tue 10/2011:52 am -
Nonstop2h 26m
Deal found 8/17$75
Mon 10/199:01 am -
Nonstop2h 28m
Wed 10/216:15 am -
Nonstop2h 26m
Deal found 8/18$76
Tue 9/299:05 am -
Nonstop2h 25m
Thu 10/811:52 am -
Nonstop2h 26m
Deal found 8/18$77
Sat 9/1910:29 pm -
Nonstop2h 18m
Mon 9/216:15 am -
Nonstop2h 20m
Deal found 8/18$81
Fri 9/2510:29 pm -
Nonstop2h 18m
Tue 9/2911:45 am -
Nonstop2h 22m
Deal found 8/18$82

Find flight deals from Denver to Ontario

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$66
(Super.com)

One-way from

$23
(Booking.com)

Popular in

June

Cheapest in

May

Average price

$220

Good round-trip deal

$161 or less

Good one-way deal

$78 or less
Provider with most accurate pricing for Denver Intl-Ontario flight deals.
Search Deals
Provider most trusted by Cheapflights users for Denver Intl-Ontario flights.
Search Deals
From Denver Intl to Ontario
Search Deals
One-way flight from Denver Intl to Ontario
Search Deals
Highest demand for flights based on searches. 11% potential increase in price ($28 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($7 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in August 2026
Search Deals
Price to beat on a round-trip flight from Denver Intl to Ontario.
Search Deals
Price to beat on a one-way flight from Denver Intl to Ontario.
Search Deals

Cheapflights Fare Finder

 
Use the filters below to find and compare flights from Denver to Ontario that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

DenverOntario

DEN Denver Intl - ONT Ontario

DENONT

Denver Intl

Sat 10/10

6:00 pm-10:11 pm

1 stop5h 11m

Ontario

Sat 10/17

6:00 am-11:56 am

1 stop4h 56m

$197

DenverOntario

DEN Denver Intl - ONT Ontario

DENONT

Denver Intl

Thu 9/17

8:50 pm-10:15 pm

Nonstop2h 25m

Ontario

Mon 9/21

8:10 am-11:20 am

Nonstop2h 10m

$252

DenverOntario

DEN Denver Intl - ONT Ontario

DENONT

Denver Intl

Thu 10/22

7:35 pm-8:58 pm

Nonstop2h 23m

Ontario

Mon 11/23

5:00 am-8:17 am

Nonstop2h 17m

$257

DenverOntario

DEN Denver Intl - ONT Ontario

DENONT

Denver Intl

Mon 11/9

7:25 pm-8:51 pm

Nonstop2h 26m

Ontario

Tue 11/10

5:00 am-8:17 am

Nonstop2h 17m

$258

DenverOntario

DEN Denver Intl - ONT Ontario

DENONT

Denver Intl

Thu 9/24

11:26 am-12:46 pm

Nonstop2h 20m

Ontario

Mon 9/28

5:00 am-8:21 am

Nonstop2h 21m

$259
Quickest round-trip

DenverOntario

DEN Denver Intl - ONT Ontario

DENONT

Denver Intl

Fri 12/11

7:05 pm-8:20 pm

Nonstop2h 15m

Ontario

Mon 12/14

5:00 am-8:11 am

Nonstop2h 11m

$265

DenverOntario

DEN Denver Intl - ONT Ontario

DENONT

Denver Intl

Mon 9/21

4:10 pm-9:30 pm

2 stops6h 20m

Ontario

Mon 9/28

4:00 pm-11:10 pm

1 stop6h 10m

$277

DenverOntario

DEN Denver Intl - ONT Ontario

DENONT

Denver Intl

Thu 10/1

10:45 am-4:35 pm

1 stop6h 50m

Ontario

Fri 10/2

1:04 pm-7:40 pm

1 stop5h 36m

$278

DenverOntario

DEN Denver Intl - ONT Ontario

DENONT

Denver Intl

Thu 9/17

4:10 pm-9:30 pm

2 stops6h 20m

Ontario

Thu 9/24

4:10 pm-11:10 pm

1 stop6h 00m

$299

DenverOntario

DEN Denver Intl - ONT Ontario

DENONT

Denver Intl

Thu 10/15

2:55 pm-8:20 pm

2 stops6h 25m

Ontario

Tue 10/20

5:40 am-1:35 pm

1 stop6h 55m

$299

Flights are sorted by cheapest round-trip flights first.

Deals found on 8/20

Showing 1-10 of 20 resultsSorted by cheapest first
1
2

Compare providers for flights from Denver to Ontario

Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Denver to Ontario in August.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy1 starTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*3 stars
JustAirTicketPrice Accuracy-Trust Score*1 star
CheapflightsfaresPrice Accuracy2 starsTrust Score*1 star
eDreamsPrice Accuracy2 starsTrust Score*3 stars
Super.comPrice Accuracy-Trust Score*3 stars
PricelinePrice Accuracy1 starTrust Score*3 stars
Kiwi.comPrice Accuracy3 starsTrust Score*3 stars
CheapfaremartPrice Accuracy-Trust Score*1 star
CheapOairPrice Accuracy3 starsTrust Score*3 stars

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on Denver-Ontario flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Denver-Ontario flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Denver-Ontario flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Denver-Ontario flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Denver-Ontario flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

Best time to book a flight from Denver to Ontario

Have a flexible travel schedule? Discover the best time to fly to Ontario from Denver with our price prediction graph.
Estimated round-trip price

Cheapflights Insights

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

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

The price you pay for your flight from Denver to Ontario may vary depending on when you book. For the best chance of a lower fare, look to book 83 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.

What is the cheapest month to book a flight from Denver to Ontario?

Currently, May is the cheapest month in which you can book a flight from Denver to Ontario (average of $176). Flying from Denver to Ontario in June is currently the most expensive (average of $290). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from DEN to ONT?

One of the essential ways to save on airfare from Denver to Ontario is to remain as flexible as possible. Flights that are at noon tend to be the most expensive. A flight in the evening could potentially save you up to 24% on airfare.

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

Travelers seeking maximum savings on their Denver to Ontario flight should consider departing on Wednesday afternoons when fares are most often at their lowest. Monday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.

How much does it cost to fly round-trip from Denver to Ontario?

Airfare is below average for this route at the moment.

Denver to Ontario flights typically cost between $123 and $256 in October.
The cheapest round-trip price found within the last 5 days was $66 on Frontier (Oct 20-Oct 21).

The best insider tips for Denver to Ontario flights

Cheapflights partnered with top experts to bring you the best recommendations for your Denver to Ontario trip
Our travel experts
Bill Fink

Bill Fink

Expert on ONT

Bill is an award-winning travel writer with extensive credits covering airlines and the aviation industry for publications including AARP, AFAR, The Points Guy and Yahoo. Based in Portland, Oregon, Bill has traveled to more than 75 countries - and been late for his flight in most of them. He once achieved top-level frequent flier status for all of American, Delta and United Airlines during a single year.

Read more
Emily Zemler

Emily Zemler

Expert on DEN

Emily is a freelance writer and book author based in London covering entertainment and travel. Her work has appeared in Los Angeles Times, Observer, and Conde Nast Traveler She has ventured to more than 40 countries and all seven continents, always in search of a great art museum. She has written extensively about hotels, luxury travel, and aviation.

Read more

Reviews of airlines servicing Ontario

Read reviews from past customers who have flown Southwest,United Airlines, andFrontier from Denver to Ontario. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,215 reviews

Entertainment

7.5

Food

7.0

Overall

8.0

Boarding

8.1

Comfort

8.0

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Anonymous,Feb 2026

DEN - BDL

Weird they cancelled a direct and rerouted me on a connecting flight to get in 10 hours later. What was the point? Crew and flight were great, but not sure what's going on with Southwest.
Southwest
8.0
Very good
4,215 reviews
Southwest
8.0
Very good
4,215 reviews

Entertainment

7.5

Food

7.0

Overall

8.0

Boarding

8.1

Comfort

8.0

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Anonymous,Feb 2026

DEN - BDL

Weird they cancelled a direct and rerouted me on a connecting flight to get in 10 hours later. What was the point? Crew and flight were great, but not sure what's going on with Southwest.
United Airlines
7.4
Good
10,105 reviews
Southwest
8.0
Very good
4,215 reviews

Entertainment

7.5

Food

7.0

Overall

8.0

Boarding

8.1

Comfort

8.0

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Anonymous,Feb 2026

DEN - BDL

Weird they cancelled a direct and rerouted me on a connecting flight to get in 10 hours later. What was the point? Crew and flight were great, but not sure what's going on with Southwest.
Frontier
5.6
Fair
2,661 reviews
Southwest
8.0
Very good
4,215 reviews

Entertainment

7.5

Food

7.0

Overall

8.0

Boarding

8.1

Comfort

8.0

Crew

8.6

Reviews

1 / 20
8.0
Excellent

Anonymous,Feb 2026

DEN - BDL

Weird they cancelled a direct and rerouted me on a connecting flight to get in 10 hours later. What was the point? Crew and flight were great, but not sure what's going on with Southwest.

Related info for your journey

  • What airports do I use to fly from Denver to Ontario?

    You will need to book a flight from Denver Intl to Ontario if you want to fly from Denver to Ontario. At least 3 different airlines have flights from Denver Intl (DEN) to Ontario (ONT) on a regular basis. There are 8 flights to Ontario from the Denver airport per day. If you manage to book one that is nonstop, then you can expect the flight time from DEN to ONT to be around 2h 15m.

  • How popular is this Denver to Ontario flight route?

    Flights from Denver Intl to Ontario have been viewed 58 times in the past calendar month.

  • How long is the flight from Denver to Ontario?

    There are many flights that can get you from Denver to Ontario in 2h 23m. Fly via Delta, Southwest, or United Airlines to get the fastest option. Airlines will cover a distance of 817 mi. This flight may include one or multiple stops.

  • What are the cheapest airlines flying from Denver to Ontario round-trip?

    According to our current data, Frontier ($66), United Airlines ($117), and Southwest ($157) offers the cheapest pricing from Denver to Ontario. Frontier is priced at 70% lower than the current average price of a flight leaving 3 months from now.

  • What are the cheapest airlines to fly from Denver to Ontario one-way?

    For one-way options, check prices for Frontier. According to our data, you can fly for as low as $33. Users have also found prices from $78 and $79 on Southwest and United Airlines, respectively.

  • What are the most reliable airlines from Denver to Ontario?

    Before booking your flight to Ontario from Denver, check out the most reliable airlines to get you to your destination on time: Frontier (75%), Volaris (75%), Southwest( 71%).

  • What are the cheapest flights from Denver to Ontario?

    The cheapest flight price from Denver to Ontario is $33. On average you can expect to pay $267. The most popular route, (Denver Intl - Ontario), can usually be booked for $82.

  • Can I find deals for flights from Denver to Ontario that include hotel bookings?

    Yes. In addition to deals on Denver to Ontario flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Denver to Ontario?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Denver to Ontario.

  • Can I find deals for business class flights from Denver to Ontario?

    Yes. Cheapflights offers flight deals from Denver to Ontario by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Denver to Ontario?

    Currently, May is the cheapest month in which you can book a flight from Denver to Ontario (average of $176). Flying from Denver to Ontario in June is currently the most expensive (average of $290). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

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Top 3 airlines flying from Denver to Ontario

AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$66Average$195FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$117Average$291FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$157Average$302FlexibilityNo cancel feeOn-time63%

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