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$55+ Cheap flights from Denver to Ontario (DEN - ONT)

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 4/23. Fares are subject to change and may not be available on all flights or dates of travel.
DEN — ONT
Mar 30 — Apr 61
Sun 3/30
Sun 4/6
1 adult, Economy
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Cheapflights Tip: The best prices from Denver Intl to Ontario are usually found in April or August, booked 40 days in advance, depart on a Tuesday or Saturday and return on a Saturday

Cheap flight deals from Denver to Ontario

Discover tips and strategies to find the most affordable flight options for your journey from Denver (DEN) to Ontario (ONT). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated March 25, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$92
(United Airlines)

One-way from

$55
(Trip.com)

Popular in

February

Cheapest in

April

Average price

$176

Good round-trip deal

$100 or less

Good one-way deal

$61 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.
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From Denver Intl to Ontario
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One-way flight from Denver Intl to Ontario
Search Deals
Highest demand for flights based on searches. 12% potential increase in price ($19 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($4 potential savings vs. average RT price).
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Average for round-trip flights in March 2025
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Price to beat on a round-trip flight from Denver Intl to Ontario.
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Price to beat on a one-way flight from Denver Intl to Ontario.
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Find flight deals from Denver to Ontario

Cheapest flights from Denver to Ontario
Explore the most affordable flight options available from Denver to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on March 25, 2025.

This United Airlines deal was found by Cheapflights users on 3/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/221:54 pmDEN - ONT
Nonstop2h 23mUnited Airlines
Tue 4/224:17 pmONT - DEN
Nonstop2h 20mUnited Airlines
Deal found 3/24$92
This Frontier deal was found by Cheapflights users on 3/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/2310:00 amDEN - ONT
Nonstop2h 20mFrontier
Wed 4/3012:10 pmONT - DEN
Nonstop2h 22mFrontier
Deal found 3/24$98
This Southwest deal was found by Cheapflights users on 3/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/226:45 pmDEN - ONT
Nonstop2h 20mSouthwest
Wed 4/234:10 pmONT - DEN
1 stop5h 50mSouthwest
Deal found 3/24$127
This Expedia deal was found by Cheapflights users on 3/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/910:37 pmDEN - ONT
Nonstop2h 22mMultiple Airlines
Tue 4/157:00 amONT - DEN
1 stop5h 53mMultiple Airlines
Deal found 3/24$151
This Alaska Airlines deal was found by Cheapflights users on 3/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/267:00 amDEN - ONT
1 stop9h 32mAlaska Airlines
Thu 5/14:29 pmONT - DEN
1 stop6h 30mAlaska Airlines
Deal found 3/24$176
This American Airlines deal was found by Cheapflights users on 3/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/168:09 amDEN - ONT
1 stop4h 50mAmerican Airlines
Tue 4/226:15 amONT - DEN
1 stop4h 15mAmerican Airlines
Deal found 3/23$199
This Delta deal was found by Cheapflights users on 3/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/287:05 amDEN - ONT
1 stop6h 10mDelta
Sat 6/71:10 pmONT - DEN
1 stop5h 20mDelta
Deal found 3/24$217
This Hawaiian Airlines deal was found by Cheapflights users on 3/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Hawaiian Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/2411:55 amDEN - ONT
1 stop6h 35mHawaiian Airlines
Mon 4/284:29 pmONT - DEN
1 stop6h 30mHawaiian Airlines
Deal found 3/24$399

Cheapflights Fare Finder

Customize your flight search to find flights from Denver to Ontario that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated March 25, 2025.
Use the filters below to find and compare flights from Denver to Ontario that are best for you.

Fly from

Denver

Fly to

Ontario

Route

Depart

Return

Price

DenverOntario

DEN - ONT

DENONT

Denver Intl

Tue 4/22

1:54 pm-3:17 pm

Nonstop2h 23m

Ontario

Tue 4/22

4:17 pm-7:37 pm

Nonstop2h 20m

$92

DenverOntario

DEN - ONT

DENONT

Denver Intl

Tue 4/22

6:45 pm-8:05 pm

Nonstop2h 20m

Ontario

Wed 4/23

1:05 pm-4:20 pm

Nonstop2h 15m

$97

DenverOntario

DEN - ONT

DENONT

Denver Intl

Wed 4/23

10:38 pm-11:59 pm

Nonstop2h 21m

Ontario

Tue 4/29

12:59 am-4:16 am

Nonstop2h 17m

$98

DenverOntario

DEN - ONT

DENONT

Denver Intl

Wed 4/9

10:37 pm-11:59 pm

Nonstop2h 22m

Ontario

Tue 4/15

7:00 am-1:53 pm

1 stop5h 53m

$151

DenverOntario

DEN - ONT

DENONT

Denver Intl

Sat 4/26

7:00 am-3:32 pm

1 stop9h 32m

Ontario

Thu 5/1

4:29 pm-11:59 pm

1 stop6h 30m

$176

DenverOntario

DEN - ONT

DENONT

Denver Intl

Wed 4/16

8:09 am-11:59 am

1 stop4h 50m

Ontario

Tue 4/22

6:15 am-11:30 am

1 stop4h 15m

$199

DenverOntario

DEN - ONT

DENONT

Denver Intl

Wed 5/28

7:05 am-12:15 pm

1 stop6h 10m

Ontario

Sat 6/7

1:10 pm-7:30 pm

1 stop5h 20m

$217

DenverOntario

DEN - ONT

DENONT

Denver Intl

Thu 4/24

11:55 am-5:30 pm

1 stop6h 35m

Ontario

Mon 4/28

4:29 pm-11:59 pm

1 stop6h 30m

$399

DenverOntario

DEN - ONT

DENONT

Denver Intl

Wed 4/23

10:38 pm-11:59 pm

Nonstop2h 21m

$55

DenverOntario

DEN - ONT

DENONT

Denver Intl

Mon 4/28

6:15 am-11:00 am

1 stop5h 45m

$79

Flights are sorted by cheapest round-trip flights first.

Deals found on 3/24

Showing 1-10 of 16 results
1
2

Compare providers for flights from Denver to Ontario

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Denver to Ontario in March.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy1 starTrust Score*3 stars
eDreamsPrice Accuracy3 starsTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*3 stars
CheapflightsfaresPrice Accuracy3 starsTrust Score*2 stars
Kiwi.comPrice Accuracy3 starsTrust Score*2 stars
CheapfaremartPrice Accuracy-Trust Score*3 stars
Justfly.comPrice Accuracy3 starsTrust Score*3 stars
MytripPrice Accuracy3 starsTrust Score*3 stars
CheapOairPrice Accuracy1 starTrust 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.

The best insider tips for Denver to Ontario flights

Snippets provided in this section are AI-generated based on a summarization of Cheapflights-commissioned articles. The articles are presented as-is, for general informational purposes only, and may not be up-to-date. The opinions contained in the articles are original to the author and reflect their authentic experience, which may vary significantly from the experience of others.
Cheapflights partnered with top experts to bring you the best recommendations for your Denver to Ontario trip
Airports
DEN

For a quick check-in, use the DEN Reserve to schedule your security time online, bypassing long lines at general security.

Read more about DENby Emily Zemler
ONT

Consider renting a car at ONT for easy access to Southern California destinations like Palm Springs and Big Bear.

Read more about ONTby Bill Fink
Our travel experts
Bill Fink

Bill Fink

Expert on ONT

Bill Fink

Bill Fink

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 Zemler

Emily Zemler

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

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
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

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?

Use this chart to determine the optimal time to book a round-trip flight from Denver to Ontario. Price data was last updated on March 21, 2025.

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 40 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, August is the cheapest month in which you can book a flight from Denver to Ontario (average of $246). Flying from Denver to Ontario in March is currently the most expensive (average of $324). 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?

Find hourly flight availability from Denver to Ontario. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated March 25, 2025.

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 morning could potentially save you up to 43% on airfare.

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

Use this chart to determine the cheapest time to fly round-trip from Denver to Ontario. Price data was last updated on March 23, 2025.

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

Weekly flight availability from Denver to Ontario

Explore weekly flight availability from Denver to Ontario. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated March 25, 2025.

The most flights from DEN to ONT are scheduled on a Monday (10 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (4 on average).

Rainfall in Ontario by month

Plan your trip to Ontario by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Ontario ranges from 0.1 - 3.4 inches per month. February is typically the wettest month, when rainfall can reach 3.4 in. June is typically the driest time to visit Ontario when rainfall is around 0.1 in.

Temperature in Ontario by month

Plan your trip to Ontario by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Ontario, use this chart to help with planning. For those seeking warmer temperatures, August is the ideal time of year to visit, when temperatures reach an average of 78.8 F. Travelers looking to avoid the cold should look outside of December, when temperatures are typically at their lowest (around 53.6 F).

Reviews of airlines servicing Ontario

Get insights into the airlines that provide service to Ontario. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Ontario. Reviews last updated March 25, 2025.
To help decide which airline to fly from Denver to Ontario, see what other customers have to say about Alaska Airlines, Southwest and Delta. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
9,782 reviews

Comfort

7.9

Boarding

8.2

Crew

8.5

Overall

8.0

Food

7.1

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

Seleste,Dec 2024

FAT - SAN

The attention and efficiency of the staff and the good handling of the pilot
Alaska Airlines
8.0
Very good
9,782 reviews
Alaska Airlines
8.0
Very good
9,782 reviews

Comfort

7.9

Boarding

8.2

Crew

8.5

Overall

8.0

Food

7.1

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

Seleste,Dec 2024

FAT - SAN

The attention and efficiency of the staff and the good handling of the pilot
Southwest
8.0
Very good
4,272 reviews
Alaska Airlines
8.0
Very good
9,782 reviews

Comfort

7.9

Boarding

8.2

Crew

8.5

Overall

8.0

Food

7.1

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

Seleste,Dec 2024

FAT - SAN

The attention and efficiency of the staff and the good handling of the pilot
Delta
8.0
Very good
7,890 reviews
Alaska Airlines
8.0
Very good
9,782 reviews

Comfort

7.9

Boarding

8.2

Crew

8.5

Overall

8.0

Food

7.1

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

Seleste,Dec 2024

FAT - SAN

The attention and efficiency of the staff and the good handling of the pilot
Hawaiian Airlines
7.9
Good
2,330 reviews
Alaska Airlines
8.0
Very good
9,782 reviews

Comfort

7.9

Boarding

8.2

Crew

8.5

Overall

8.0

Food

7.1

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

Seleste,Dec 2024

FAT - SAN

The attention and efficiency of the staff and the good handling of the pilot
United Airlines
7.4
Good
8,605 reviews
Alaska Airlines
8.0
Very good
9,782 reviews

Comfort

7.9

Boarding

8.2

Crew

8.5

Overall

8.0

Food

7.1

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

Seleste,Dec 2024

FAT - SAN

The attention and efficiency of the staff and the good handling of the pilot

Related info for your journey

Find useful and relevant information for your journey from Denver to Ontario. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • 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 7 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 83 times in the past calendar month.

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

    According to our current data, United Airlines ($92), Frontier ($98), and Southwest ($127) offers the cheapest pricing from Denver to Ontario. United Airlines is priced at 33% 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 $55. Users have also found prices from $79 and $82 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: Air Canada (86%), United Airlines (82%), Southwest( 74%).

  • What are the cheapest flights from Denver to Ontario?

    The cheapest flight price from Denver to Ontario is $31. On average you can expect to pay $135. The most popular route, (Denver Intl - Ontario), can usually be booked for $92.

  • 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, August is the cheapest month in which you can book a flight from Denver to Ontario (average of $246). Flying from Denver to Ontario in March is currently the most expensive (average of $324). 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.

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Alternative routes for Denver to Ontario

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Top 3 airlines flying from Denver to Ontario

Discover the top 3 airlines that operate flights from Denver to Ontario. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated March 25, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$52Average$122FlexibilityNo cancel feeOn-time62%
SouthwestCheapest$117Average$245FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$136Average$308FlexibilityNo cancel feeOn-time69%
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