£158 Cheap Flights from Ontario (ONT) to Denver (DEN)

View £158 flight on Sat, 2 May 2026Opens in a new window

Popular airlines from Los Angeles - Ontario Intl. Airport (ONT) to Denver International Airport (DEN)

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Cheap Flights from Ontario (ONT) to Denver (DEN)

Prices were available within the past 7 days and start at £158 for one-way flights and £336 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Alaska Airlines
Wed, 14 Oct - Wed, 21 Oct
ONT
Ontario
DEN
Denver
£336 Return, found 5 days ago
£336
Return
found 5 days ago
Select Alaska Airlines flight, departing Wed, 14 Oct from Ontario to Denver, returning Wed, 21 Oct, priced at £336 found 5 days ago
Alaska Airlines
Wed, 19 Aug - Mon, 24 Aug
ONT
Ontario
DEN
Denver
£346 Return, found 4 days ago
£346
Return
found 4 days ago
Select Alaska Airlines flight, departing Wed, 19 Aug from Ontario to Denver, returning Mon, 24 Aug, priced at £346 found 4 days ago
Alaska Airlines
Fri, 9 Oct - Fri, 16 Oct
ONT
Ontario
DEN
Denver
£353 Return, found 5 days ago
£353
Return
found 5 days ago
Select Alaska Airlines flight, departing Fri, 9 Oct from Ontario to Denver, returning Fri, 16 Oct, priced at £353 found 5 days ago
Alaska Airlines
Thu, 20 Aug - Mon, 24 Aug
ONT
Ontario
DEN
Denver
£355 Return, found 4 days ago
£355
Return
found 4 days ago
Select Alaska Airlines flight, departing Thu, 20 Aug from Ontario to Denver, returning Mon, 24 Aug, priced at £355 found 4 days ago
Alaska Airlines
Wed, 19 Aug - Mon, 24 Aug
ONT
Ontario
DEN
Denver
£358 Return, found 4 days ago
£358
Return
found 4 days ago
Select Alaska Airlines flight, departing Wed, 19 Aug from Ontario to Denver, returning Mon, 24 Aug, priced at £358 found 4 days ago
Alaska Airlines
Fri, 9 Oct - Fri, 16 Oct
ONT
Ontario
DEN
Denver
£366 Return, found 5 days ago
£366
Return
found 5 days ago
Select Alaska Airlines flight, departing Fri, 9 Oct from Ontario to Denver, returning Fri, 16 Oct, priced at £366 found 5 days ago
Alaska Airlines
Wed, 19 Aug - Mon, 24 Aug
ONT
Ontario
DEN
Denver
£367 Return, found 4 days ago
£367
Return
found 4 days ago
Select Alaska Airlines flight, departing Wed, 19 Aug from Ontario to Denver, returning Mon, 24 Aug, priced at £367 found 4 days ago
Alaska Airlines
Sun, 26 Apr - Mon, 27 Apr
ONT
Ontario
DEN
Denver
£374 Return, found 4 days ago
£374
Return
found 4 days ago
Select Alaska Airlines flight, departing Sun, 26 Apr from Ontario to Denver, returning Mon, 27 Apr, priced at £374 found 4 days ago
Alaska Airlines
Wed, 19 Aug - Mon, 24 Aug
ONT
Ontario
DEN
Denver
£379 Return, found 4 days ago
£379
Return
found 4 days ago
Select Alaska Airlines flight, departing Wed, 19 Aug from Ontario to Denver, returning Mon, 24 Aug, priced at £379 found 4 days ago
JetBlue Airways
Wed, 14 Oct - Wed, 21 Oct
ONT
Ontario
DEN
Denver
£420 Return, found 5 days ago
£420
Return
found 5 days ago
Select JetBlue Airways flight, departing Wed, 14 Oct from Ontario to Denver, returning Wed, 21 Oct, priced at £420 found 5 days ago

Alternative airports near Denver

Prices were available within the past 7 days. Prices and availability are subject to change.

Select flight to Denver Intl. DEN. Cheapest option available. Average driving time to city centre is 32 minutes. Flights from £263
DEN
Denver Intl.
Cheapest
Average driving time to city centre32 min
Flights from £263

Frequently asked questions

How much is a flight from Los Angeles - Ontario Intl. Airport (ONT) to DIA airport?
Within the past 7 days on Expedia, for flights departing within the next year, the lowest price listed for a round-trip journey from ONT to DIA airport was £336. Cheap tickets don't hang around forever, so make sure you book yours today. Prices and availability are subject to change. Additional terms apply.
Do I need to pay a cancellation fee if I cancel my flight from Ontario Airport to Denver Intl. Airport (DEN)?
Every air carrier has its own set of terms and conditions. If you do decide to cancel, follow the simple instructions on our Customer Service Portal.
How do I find cheap flights from Ontario Airport to DIA airport that have flexible change policies?
Many airlines offer the option to reschedule your flight without a change fee. All you pay is the difference between the original flight and the new flight. When you're searching for ONT to Denver Airport flights, you'll see a "no change fees" filter for you to select.
How far is the flight from Los Angeles - Ontario Intl. Airport (ONT) to Denver Intl. Airport (DEN)?
Forget about a movie marathon on this flight — it's just 1,300 kilometres from Ontario to Denver. Find your seat, enjoy the in-flight service and you'll be touching down in no time.
Which airlines fly direct from Ontario Airport to DEN?
There are a few airlines that travel directly from Los Angeles - Ontario Intl. Airport (ONT) to Denver Intl. Airport (DEN). Southwest Airlines (WN) is a top choice, offering 117 flights on this route each month. Frontier Airlines (F9) is another popular choice. It operates 60 flights per month. Between these two airlines, you'll be able to find a great deal from Ontario to Denver.
Are Los Angeles - Ontario Intl. Airport (ONT) to DEN flight tickets cheaper when they're purchased at the last minute?
Flight prices go up and down like a yo-yo, so not always. While last-minute flight deals between Los Angeles - Ontario Intl. Airport (ONT) and Denver Intl. Airport (DEN) are of course possible, it also makes sense to keep an eye on prices well before you fly. In fact, some airlines publish their prices up to a year before the departure date. Expedia is continuously updating the biggest airfare bargains around, so keep checking and be ready to pounce when the price dips.

Frequently asked questions

How much does a flight from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.) cost?
One-way flights typically cost between £578 and £1,514 and return flights often range between £578 and £1,514. Flight prices vary based on the month and day of the week you want to travel, as well as the airline and how far in advance you book your ticket. Filter your search on Expedia by "Price (lowest to highest)" to see the cheapest fares first, and use the Price Tracking tool to receive alerts when Anaa (AAA) to Toronto, ON (YYZ-Pearson Intl.) ticket fares go up or down.
Which airlines fly direct from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.)?
Enter ONT to DEN and your travel dates, then apply the 'Nonstop' filter to see only direct flights.
How do I find cheap flights from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.)?
To find a cheap flight from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.), be flexible with your dates. Traveling outside of peak vacation months and booking a mid-week flight can help you save. Early morning and late night flights are often more affordable, too. Expedia allows you to compare flight times, airlines and routes all in one place to find low fares. You can also set up Price Tracking and receive alerts when fares go up or down.
What is the best airline to fly with from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.)?
The best airline to fly with from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.) will differ from traveller to traveller. If you like to fly early, UA offers early morning flights. If price is the most important factor, F9 typically offers the lowest fares. WN offers the most daily flights from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.), which is brilliant if flexibility is what you value most. The best carrier for this journey could also be the one you have a loyalty membership with, as flying with that airline or another airline within the same alliance could help you collect points or enjoy lounge access.
What is the best time to fly from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.)?
The best time to fly is usually mid-week (Tuesday or Wednesday) and during early morning hours as flights tend to be cheaper, less crowded, and generally more on-time. Avoid major holidays and peak vacation seasons for smoother travel. Combining off-peak days and hours often gives the best combination of cost, comfort, and convenience.
How many flights per day from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.)?
There are approximately 8 nonstop flights per day from Los Angeles - Ontario Intl. (ONT) to Denver Intl. (DEN). For even more choice, look at flights that include layovers, as there are around 75 connecting flights per day. Some common connection points include McCarran Intl. (LAS), Sky Harbor Intl. (PHX), and Portland Intl. (PDX).
What is the earliest flight from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.)?
The earliest flight from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.) typically departs at approximately 12:05 AM local time, operated by Frontier Airlines. This is a seasonal service active in May. An early departure like this can help you maximise your time at your destination. To compare early flights on Expedia, select the "Early Morning" and "Morning" filters in your search.
What day of the week has the most flights from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.)?
You'll typically find the most flights from Los Angeles - Ontario Intl. (ONT) to Denver Intl. (DEN) on a Friday, with around 62 flights available. This gives you plenty of options for your travel plans. Major airlines on this route include Southwest Airlines, Alaska Airlines, and American Airlines. Fridays offer notably more flight options compared to other days of the week.
What are the most popular departure times for flights from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.)?
The most popular departure times for flights from Los Angeles - Ontario Intl. (ONT) to Denver Intl. (DEN) are in the early morning, from 6am to 9am. Approximately 30% of passengers prefer this time window. Many major carriers, including Frontier Airlines and Southwest Airlines, offer flights during this window. This timing works well because you can get an early start to your travel day and arrive in Denver with plenty of time.
How long does it take to fly from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.)?
Flying nonstop from ONT to DEN takes around 2 hours 20 minutes, with the route covering approximately 817 miles. Flights with a layover typically take 5 hours 40 minutes longer than direct options. Keep in mind that actual flight times can vary due to wind patterns, weather, and air traffic.
Can you fly business or first class from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.)?
Select the "Business class" and "First class" filters when looking for ONT to DEN flights on Expedia. This is the easiest way to compare prices, routes and flight times for your trip.
How do I earn miles on a Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.) flight with Expedia?
It's easy to earn miles on a Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.) flight when you book with Expedia. Before you confirm your booking, simply select your frequent flyer program and enter your program number. As a member of One Key™, you can also earn OneKeyCash™* on top of your airline miles when you book with Expedia. *Excludes taxes and fees. OneKeyCash is not redeemable for cash and can only be used on Expedia and other participating brands.
What airports do you fly into for Denver from Los Angeles - Ontario Intl. (ONT)?
From Los Angeles - Ontario Intl. (ONT), you can fly directly into Denver Intl. (DEN) to reach Denver. Some flights may connect through major hubs like Portland Intl. (PDX), Seattle - Tacoma Intl. (SEA), McCarran Intl. (LAS) before reaching Denver. Compare routes and airports on Expedia to find the best flight options for your travel plans.
Is it cheaper to buy a plane ticket from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.) at the last minute?
Typically, booking a last minute flight from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.) will be more expensive than booking in advance. As the departure date approaches, there are usually fewer seats available which can drive up the cost. However, if there's some wiggle room with your travel dates and times, you could bag a cheap last-minute fare.
Is it cheaper to book a Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.) flight and hotel package?
Securing a Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.) flight and hotel package is usually cheaper than booking separately. With Expedia, you can enjoy the ease of organizing your travels all in one place. Select from our extensive range of stays and then add flights, activities and car rentals to your booking. Bundle everything together, and you could save hundreds of dollars.
Can I cancel or change the date of my flight from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.)?
If you booked your Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Denver, CO (DEN-Denver Intl.) flight within the last 24 hours, you may be able to modify or cancel it without any fees. Depending on the airline and the type of ticket you have, additional charges may apply for changes beyond this timeframe. Airline policies and contact information can be found in your itinerary or confirmation email. Or, head to our Customer Service portal if you'd like more information.

Travel information

Origin airport
Los Angeles - Ontario Intl.
Destination airport
Denver Intl.
Airlines serving
Alaska Airlines
Return price
£336
Distance
1306 km
Average flight time
3 hours 25 mins

Book with confidence

Compare flights from Ontario to Denver easily and book with confidence

For travelling on business or for pleasure, Expedia makes it easy to book your flights from Ontario to Denver. Operating between them flights per day, 20 airlines cover the route. And fly direct, getting you to Denver Intl. in just hours. If you have a preferred carrier, use our advanced search tool to find the right flight from Los Angeles - Ontario Intl. to Denver Intl..  

To make things even better, in the advanced search, you can also choose to fly economy, premium economy, business or first class, select your maximum number of stops, and pick your preferred departure and arrival time. You can also opt for refundable and direct flights. 

Grab a great deal on your flight from Los Angeles - Ontario Intl. (ONT) to Denver Intl. (DEN)

The easiest way to view the best deals on flights from Ontario to Denver today is to enter your travel dates and hit search. From here, you can sort your results by price to see the cheapest flights first. Right now, return flights from Los Angeles - Ontario Intl. to Denver Intl. start at just £336 and range up to £420.  

To find an even better deal, try  

  • being flexible on your dates – midweek flights can be cheaper
  • looking for other airports near Ontario and Denver
  • booking your flight during October, the cheapest month on this route
  • varying your flight times – early morning and late at night are sometimes cheaper 

Why you should book your Ontario to Denver flight with Expedia!

We cater for all flight types, cabin classes and airlines. So whether you’re booking flights from Los Angeles - Ontario Intl. to Denver Intl. for a budget break or a business trip with a bit of pleasure thrown in, we make it easy to secure the seat that’s right for you.  

Thanks to our supersized inventory that offers great choice all in one place, you know you’ll get a great deal with Expedia. Especially if you bundle your flight together with your hotel, you will unlock amazing savings. For added peace of mind, you can choose flexible bookings or filter to find refundable options, so you won’t pay a fee to change your flight.  

Compare flights from Ontario to Denver easily and book with confidence

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