HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Denver

$29+ Cheap flights from Ontario to Denver (ONT - DEN)

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 2/1. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — DEN
Jan 28 — Feb 41
Tue 1/28
Tue 2/4
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Ontario to Denver 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.

The best prices from Ontario to Denver Intl are usually found in January or September, booked 88 days in advance, depart on a Saturday or Friday and return on a Tuesday

Cheap flight deals from Ontario to Denver

Discover tips and strategies to find the most affordable flight options for your journey from Ontario (ONT) to Denver (DEN). 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 January 23, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$58
(Frontier)

One-way from

$29
(Frontier)

Popular in

March

Cheapest in

January

Average price

$128

Good round-trip deal

$136 or less

Good one-way deal

$91 or less
Provider with most accurate pricing for Ontario-Denver Intl flight deals.
Search Deals
Provider most trusted by Cheapflights users for Ontario-Denver Intl flights.
Search Deals
From Ontario to Denver Intl
Search Deals
One-way flight from Ontario to Denver Intl
Search Deals
Highest demand for flights based on searches. 1% potential increase in price ($1 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 1% potential price decrease ($3 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in January 2025
Search Deals
Price to beat on a round-trip flight from Ontario to Denver Intl.
Search Deals
Price to beat on a one-way flight from Ontario to Denver Intl.
Search Deals

Find flight deals from Ontario to Denver

Cheapest flights from Ontario to Denver
Explore the most affordable flight options available from Ontario to Denver. Find the lowest fares from popular airlines and budget airlines, with prices last updated on January 23, 2025.

This Frontier deal was found by Cheapflights users on 1/23. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 2/1812:59 amONT - DEN
Nonstop2h 17mFrontier
Sat 2/2210:37 pmDEN - ONT
Nonstop2h 32mFrontier
Deal found 1/23$58
This Southwest deal was found by Cheapflights users on 1/22. 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.
Sat 2/224:30 pmONT - DEN
Nonstop2h 10mSouthwest
Thu 2/2710:25 pmDEN - ONT
Nonstop2h 30mSouthwest
Deal found 1/22$177
This United Airlines deal was found by Cheapflights users on 1/23. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 2/221:44 pmONT - DEN
Nonstop2h 19mUnited Airlines
Sat 2/227:25 pmDEN - ONT
Nonstop2h 27mUnited Airlines
Deal found 1/23$212
This Delta deal was found by Cheapflights users on 1/23. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 2/221:21 pmONT - DEN
1 stop5h 00mDelta
Mon 2/246:05 pmDEN - ONT
1 stop6h 46mDelta
Deal found 1/23$217

Find flights from Ontario to Denver within your budget

Customize your flight search to find flights from Ontario to Denver 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 January 23, 2025.

Fly from

Any airport

Fly to

Any airport

Route

Depart

Return

Price

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 2/1

6:45 am-10:04 am

Nonstop2h 19m

Denver Intl

Tue 2/4

10:15 pm-11:47 pm

Nonstop2h 32m

$58

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 2/22

4:30 pm-7:40 pm

Nonstop2h 10m

Denver Intl

Thu 2/27

10:25 pm-11:55 pm

Nonstop2h 30m

$177

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 2/22

1:44 pm-5:03 pm

Nonstop2h 19m

Denver Intl

Sat 2/22

7:25 pm-8:52 pm

Nonstop2h 27m

$212

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 2/1

6:45 am-10:04 am

Nonstop2h 19m

$29

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 3/1

5:05 am-8:24 am

Nonstop2h 19m

$79

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sun 2/23

5:15 am-8:25 am

Nonstop2h 10m

$99

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 2/25

6:13 am-11:40 am

1 stop4h 27m

$100

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 2/25

6:00 am-4:12 pm

1 stop9h 12m

$108

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 2/25

4:05 pm-12:17 am

1 stop7h 12m

$109

Flights are sorted by cheapest round-trip flights first.

Deals found on 1/23

Compare providers for flights from Ontario to Denver

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 Ontario to Denver in January.
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*1 star
CheapOairPrice Accuracy2 starsTrust Score*2 stars
PricelinePrice Accuracy2 starsTrust Score*3 stars
Kiwi.comPrice Accuracy3 starsTrust Score*3 stars
Justfly.comPrice Accuracy3 starsTrust Score*3 stars
CheapTicketsDealPrice 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 Ontario-Denver flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Ontario-Denver flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Ontario-Denver flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Ontario-Denver 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 Ontario-Denver 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 Ontario to Denver

Have a flexible travel schedule? Discover the best time to fly to Denver from Ontario 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.

Travel insights for flights from Ontario to Denver

Get recent, data-driven insights about flights from Ontario to Denver including ideal travel times, pricing trends, and more.

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

Use this chart to determine the optimal time to book a round-trip flight from Ontario to Denver. Price data was last updated on January 17, 2025.

The price you pay for your flight from Ontario to Denver may vary depending on when you book. For the best chance of a lower fare, look to book 88 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 Ontario to Denver?

Currently, October is the cheapest month in which you can book a flight from Ontario to Denver (average of $197). Flying from Ontario to Denver in March is currently the most expensive (average of $278). 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 ONT to DEN?

Find hourly flight availability from Ontario to Denver. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated January 23, 2025.

It’s typically best to fly out from Ontario to Denver in the evening. Doing so could potentially save you 51% on the flight price compared to flying at noon, which is usually more expensive.

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

Use this chart to determine the cheapest time to fly round-trip from Ontario to Denver. Price data was last updated on January 21, 2025.

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

Weekly flight availability from Ontario to Denver

Explore weekly flight availability from Ontario to Denver. 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 January 23, 2025.

The most flights from ONT to DEN are scheduled on a Monday (13 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (1 on average).

Rainfall in Denver by month

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

In terms of precipitation, rainfall in Denver ranges from 0.5 - 2.3 inches per month. May is typically the wettest month, when rainfall can reach 2.3 in. January is typically the driest time to visit Denver when rainfall is around 0.5 in.

Temperature in Denver by month

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

If weather is an important factor for your trip to Denver, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 73.4 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 30.2 F).

Reviews of airlines servicing Denver

Get insights into the airlines that provide service to Denver. 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 Denver. Reviews last updated January 23, 2025.
To help decide which airline to fly from Ontario to Denver, see what other customers have to say about Southwest and United Airlines. 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
8.1
Very good
4,647 reviews

Entertainment

7.7

Comfort

8.1

Food

7.2

Boarding

8.2

Crew

8.7

Overall

8.1

Reviews

1 / 10

My original flight was delayed so they found this flight for me so I could arrive at a reasonable time

Southwest
8.1
Very good
4,647 reviews
Southwest
8.1
Very good
4,647 reviews

Entertainment

7.7

Comfort

8.1

Food

7.2

Boarding

8.2

Crew

8.7

Overall

8.1

Reviews

1 / 10

My original flight was delayed so they found this flight for me so I could arrive at a reasonable time

Alaska Airlines
8.0
Very good
9,699 reviews
Southwest
8.1
Very good
4,647 reviews

Entertainment

7.7

Comfort

8.1

Food

7.2

Boarding

8.2

Crew

8.7

Overall

8.1

Reviews

1 / 10

My original flight was delayed so they found this flight for me so I could arrive at a reasonable time

Delta
8.0
Very good
8,508 reviews
Southwest
8.1
Very good
4,647 reviews

Entertainment

7.7

Comfort

8.1

Food

7.2

Boarding

8.2

Crew

8.7

Overall

8.1

Reviews

1 / 10

My original flight was delayed so they found this flight for me so I could arrive at a reasonable time

United Airlines
7.4
Good
8,970 reviews
Southwest
8.1
Very good
4,647 reviews

Entertainment

7.7

Comfort

8.1

Food

7.2

Boarding

8.2

Crew

8.7

Overall

8.1

Reviews

1 / 10

My original flight was delayed so they found this flight for me so I could arrive at a reasonable time

American Airlines
7.2
Good
10,000 reviews
Southwest
8.1
Very good
4,647 reviews

Entertainment

7.7

Comfort

8.1

Food

7.2

Boarding

8.2

Crew

8.7

Overall

8.1

Reviews

1 / 10

My original flight was delayed so they found this flight for me so I could arrive at a reasonable time

Related info for your journey

Find useful and relevant information for your journey from Ontario to Denver. 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 Ontario to Denver?

    If you book a flight from Ontario to Denver, you will be flying from Ontario to Denver Intl. Flights to Denver Intl (DEN) from Ontario (ONT) take 2h 14m for a nonstop flight. There are 8 flights from Ontario to Denver per day from 4 airlines.

  • How popular is this Ontario to Denver flight route?

    The Ontario to Denver Intl flight path was viewed by 321 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

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

    Currently priced at $58, Frontier will fly you from Ontario to Denver and back. In addition to Frontier, many other airlines offer competitively priced options for your trip. Search Cheapflights for deals from Southwest and United Airlines - these airlines can fly you to your destination from $177 and $212, respectively. These flights start at 60% lower than the current average price 3 months from now.

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

    For one-way options, check prices for Frontier. According to our data, you can fly for as low as $29. Users have also found prices from $79 and $99 on United Airlines and Southwest, respectively.

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

    The top 3 most reliable airlines when flying from Ontario to Denver are Air Canada (93%), United Airlines (89%) and Southwest (87%).

  • What are the cheapest flights from Ontario to Denver?

    While on average a flight from Ontario to Denver is generally $783, our data shows the cheapest flight currently is $38. When looking at the most popular route, (Ontario - Denver Intl), you can expect to pay $62 for that flight.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Ontario to Denver 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 Ontario to Denver?

    Currently, October is the cheapest month in which you can book a flight from Ontario to Denver (average of $197). Flying from Ontario to Denver in March is currently the most expensive (average of $278). 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

Traveling to a place near Ontario?

Book flights to Ontario if you plan to visit one of these locations
Keystone
Westminster
Black Hawk
Winter Park
Dillon
Lakewood
Broomfield
Silverthorne
Golden
Brighton
Frisco
Wheat Ridge
Grand Lake
Idaho Springs
Greeley
Central City
Copper Mountain
Longmont
Thornton
Limon

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Ontario to Denver

See prices for flight routes from nearby airports that may be better suited for you.
Los Angeles to Denver flights
San Francisco to Denver flights
Santa Ana to Denver flights
San Diego to Denver flights
San Jose to Denver flights
Sacramento to Denver flights
Los Angeles to Aspen flights
Las Vegas to Denver flights
Burbank to Denver flights
San Francisco to Aspen flights
Palm Springs to Denver flights
San Francisco to Vail flights
Los Angeles to Vail flights
Oakland to Denver flights
San Luis Obispo to Denver flights
Los Angeles to Hayden flights
Reno to Denver flights
Ontario to Aspen flights
Los Angeles to Colorado Springs flights
Santa Barbara to Denver flights
San Diego to Hayden flights
Ontario to Colorado Springs flights
Long Beach to Denver flights
Fresno to Denver flights
San Diego to Colorado Springs flights
Santa Ana to Aspen flights
San Diego to Aspen flights
San Diego to Vail flights
Los Angeles to Durango flights
Los Angeles to Grand Junction flights
San Francisco to Colorado Springs flights
Monterey to Denver flights
Ontario to Vail flights
San Francisco to Grand Junction flights
Bakersfield to Denver flights
Las Vegas to Colorado Springs flights
Medford to Denver flights
San Diego to Durango flights
Santa Ana to Hayden flights
San Francisco to Montrose flights
Santa Ana to Vail flights
Burbank to Aspen flights
Santa Rosa to Denver flights
Oakland to Colorado Springs flights
San Jose to Aspen flights
Los Angeles to Montrose flights
Ontario to Durango flights
Burbank to Vail flights
Long Beach to Colorado Springs flights

Top 4 airlines flying from Ontario to Denver

Discover the top 4 airlines that operate flights from Ontario to Denver. 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 January 23, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$52Average$131FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$148Average$293FlexibilityNo cancel feeOn-time69%
DeltaCheapest$159Average$232FlexibilityNo cancel feeOn-timeN/A
SouthwestCheapest$178Average$254FlexibilityNo cancel feeOn-time63%
100% Free
Cheapflights is completely free to use, so you can start saving the moment you arrive.
Book with Flexibility
Our users can plan ahead with confidence and find flights with no change fees
Travel Smart
Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.