ONT - DEN

$32 Find Cheap Flights from Ontario to Denver - Compare and Save

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1 adult, Economy, 0 bags

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Everything you should know

Cheapest round-trip
$87
Typical prices: $157-$332
Frontier
Mon 11/19Tue 11/27
ONT - DEN • Non-stop
Cheapest one-way
$32
Typical prices: $105-$223
Frontier
Mon 11/5
ONT - DEN • Non-stop
Nonstop flights
You can fly direct with Southwest, Frontier and United Airlines. Average duration is 2h 17m
Direct flights
+1
Direct flights
+1
When to book
in advance
Our data shows that travelers who book at least 7 weeks in advance save around 49% compared to booking last minute.
Insights
Insights
When to travel
Cheapest • 29% price drop
Most popular
Good to know
+1
Good to know
+1
Top layover airports
Cheapest • Avg $252 (round-trip)
Shortest trip • 5h 35m (one-way)
Insights
Insights
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We hope you love your trip to Denver!

Cheap Flights from Ontario to Denver (ONT-DEN)

 

Cheap flights from Ontario to Denver with top airlines, updated regularly. Compare round-trip, one-way, direct and last-minute deals.

Tue, Nov 24 - Tue, Dec 1
Frontier Logo
6:45 am - 10:06 amONT  Ontario-DEN Denver Intl
2h 21mnonstop
Frontier Logo
8:55 pm - 10:20 pmDEN  Denver Intl-ONT Ontario
2h 25mnonstop
$87Frontier
Fri, Nov 13 - Fri, Nov 13
Frontier Logo
6:30 am - 9:51 amONT  Ontario-DEN Denver Intl
2h 21mnonstop
Frontier Logo
10:29 pm - 11:51 pmDEN  Denver Intl-ONT Ontario
2h 22mnonstop
$87Frontier
Tue, Nov 17 - Wed, Nov 18
Multiple Airlines Logo
6:30 am - 9:51 amONT  Ontario-DEN Denver Intl
2h 21mnonstop
Multiple Airlines Logo
12:12 pm - 6:17 pmDEN  Denver Intl-ONT Ontario
7h 05m1 stop Seattle/Tacoma Intl
$125Multiple Airlines
Mon, Nov 9 - Sat, Nov 14
Multiple Airlines Logo
7:13 pm - 11:14 amONT  Ontario-DEN Denver Intl
15h 01m1 stop Seattle/Tacoma Intl
Multiple Airlines Logo
9:17 am - 10:42 amDEN  Denver Intl-ONT Ontario
2h 25mnonstop
$127Multiple Airlines
Fri, Nov 13 - Fri, Nov 13
Southwest Logo
6:30 am - 9:45 amONT  Ontario-DEN Denver Intl
2h 15mnonstop
Southwest Logo
6:30 pm - 7:50 pmDEN  Denver Intl-ONT Ontario
2h 20mnonstop
$157Southwest
Thu, Dec 24 - Thu, Dec 31
Southwest Logo
1:55 pm - 5:05 pmONT  Ontario-DEN Denver Intl
2h 10mnonstop
Southwest Logo
8:15 pm - 9:40 pmDEN  Denver Intl-ONT Ontario
2h 25mnonstop
$157Southwest
Fri, Jan 8 - Mon, Jan 11
United Airlines Logo
1:42 pm - 5:01 pmONT  Ontario-DEN Denver Intl
2h 19mnonstop
United Airlines Logo
7:35 pm - 9:00 pmDEN  Denver Intl-ONT Ontario
2h 25mnonstop
$166United Airlines
Fri, Jan 8 - Mon, Jan 11
United Airlines Logo
5:00 am - 8:21 amONT  Ontario-DEN Denver Intl
2h 21mnonstop
United Airlines Logo
5:05 am - 9:57 amDEN  Denver Intl-ONT Ontario
5h 52m1 stop San Francisco
$197United Airlines
Tue, Dec 1 - Tue, Dec 1
Delta Logo
6:00 am - 11:59 amONT  Ontario-DEN Denver Intl
4h 59m1 stop Salt Lake City
Delta Logo
6:11 pm - 11:57 pmDEN  Denver Intl-ONT Ontario
6h 46m1 stop Salt Lake City
$197Delta
Fri, Nov 13 - Sat, Nov 14
Delta Logo
1:15 pm - 8:29 pmONT  Ontario-DEN Denver Intl
6h 14m1 stop Salt Lake City
Delta Logo
8:10 am - 12:17 pmDEN  Denver Intl-ONT Ontario
5h 07m1 stop Salt Lake City
$197Delta

Price, demand and travel trends for Ontario to Denver flights

Use KAYAK data on prices, travel dates, airlines and seasonal trends to compare options and book flights with more confidence.

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

Round-trip flights from Ontario to Denver typically range from $157 to $332. The lowest price found in the past 5 days was $87, on Frontier.

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

Based on deals KAYAK users found in the last 12 months, Wednesday is the cheapest day of the week to fly from Ontario to Denver. It’s 18% cheaper than the average day, while Sunday is the most expensive, with prices 22% higher.

What’s the cheapest month to fly from Ontario to Denver?

•February is the cheapest month to fly from Ontario to Denver at $168 round-trip.
•June ($329) and July ($305) are the most expensive months.
•The price difference between flying in the cheapest and most expensive months is 95% on average.
This is based on KAYAK aggregated and averaged internal data over the past 12 months.

When are flights from Ontario to Denver the cheapest?

Flights from Ontario to Denver are cheapest 7 weeks before departure. Booking in this window typically costs about 49% less than the average last-minute fare (within 2 weeks of the flight), based on KAYAK data.

Expert advice for your flight from Ontario to Denver

 
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.

Key details for Ontario to Denver flights

Low season

August

Cheapest flight

$32
Beat the crowds with an average 13% drop in travelers.
The most popular month to fly with an average 12% increase in travelers.
One-way flight from Ontario to Denver

When to book flights from Ontario to Denver

Are your dates flexible? Find out the best times to travel from Ontario to Denver based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price

Your Ontario to Denver flight questions, answered

Find helpful answers about this route, including flight times, airports, airlines and booking tips.

  • What are the earliest and latest flights from Ontario to Denver?

    These are the earliest and latest flight times available from Ontario to Denver:

    • Earliest: departs at 5:00 am and lands at 7:17 am
    • Latest: departs at 5:40 pm and lands at 7:57 pm.

    The flight takes about 2h 17m.

  • What cabin classes can I book on flights from Ontario to Denver?

    Four cabin classes are available on flights from Ontario to Denver:

    • Economy Class
    • Premium Economy Class
    • Business Class
    • First Class

    Prices vary by airline.

  • How long is a flight from Ontario to Denver?

    A nonstop flight from Ontario to Denver takes 2h 17m, covering 817 miles.

  • Do I need a passport to fly from Ontario to Denver?

    No, a passport is not required for this domestic route, but you will need a real ID-compliant driver's license, a state ID or another TSA-accepted form of identification.

  • How much should I expect to pay for a Ontario to Denver flight?

    Round-trip flights from Ontario to Denver range from $157 to $332, with an average of $238 over the past 12 months. Anything below $157 counts as a good deal.

  • How expensive are last-minute Ontario to Denver flights?

    Last-minute fares on this route (booked within two weeks of departure) run 34% above the $238 route average. Book 7 weeks before departure for the lowest fares.

  • How much can I save by taking a layover when flying from Ontario to Denver?

    On this route, nonstop flights are cheaper than layover options on average. Nonstop fares average $238 round-trip, compared to $252 via a layover through Phoenix Sky Harbor Intl (PHX).

  • What is the standard checked-bag allowance on flights from Ontario to Denver?

    There is no standard. Checked-bag policies vary by airline on this route. Most carriers charge $40–$100 for the first checked bag in economy. Premium fares and elite-status bookings typically include a free checked bag.

  • Which aircraft model is used most often on flights from Ontario to Denver?

    The Airbus A320neo family is used most often on this route, operated mainly by Frontier. Other aircraft seen on the route include Boeing 737 MAX 8 variants.

  • How are flight departures from Ontario to Denver spread across the day?

    Morning is the busiest departure period on Ontario to Denver flights, with 63% of flights leaving in that window. Afternoon departures account for 37%, evening flights for 0%, and night flights for 0%.

  • How are flight prices from Ontario to Denver looking right now?

    One-way fares from Ontario to Denver are currently lower than usual. Average one-way flight prices are about $76, which is 54% below the typical average for this route.

  • What car rental options are available at Denver Intl Airport (DEN)?

    Denver Intl Airport (DEN) hosts 5 major car rental companies, with daily rates starting from around $15 for economy cars. Top options include:

    • Routes Car & Truck Rentals
    • Ace
    • Europcar
    • NU Car
    • Hertz

  • Which airports can I use when flying from Ontario to Denver?

    Flights from Ontario to Denver usually depart from Ontario (ONT) and arrive at Denver Intl (DEN).

  • Which airports do connecting flights from Ontario to Denver pass through?

    One-stop flights from Ontario to Denver most commonly connect through:

    • Las Vegas Harry Reid Intl (LAS) - 85% of one-stop connections
    • Salt Lake City (SLC) - 11% of one-stop connections
    • Phoenix Sky Harbor Intl (PHX) - 3% of one-stop connections
    • San Francisco (SFO) - 2% of one-stop connections

  • Can I save money by using flexible dates for flights from Ontario to Denver?

    Yes. Flexible dates can save you up to 33% on flights from Ontario to Denver. Wednesday is the cheapest departure day at $196 round-trip on average, while Sunday is the most expensive at $292, a difference of $96.

    KAYAK's flexible dates feature shows options up to 3 days before and after your selected dates, making it easier to compare nearby fares.

  • What airlines fly from Ontario to Denver?

    3 airlines operate flights between Ontario and Denver. The airlines offering nonstop flights on this route include:

    • Southwest
    • Frontier
    • United Airlines

  • How much time can I save by choosing a different layover airport from Ontario to Denver?

    Flying via Phoenix Sky Harbor Intl (PHX) gives the shortest average 1-stop total travel time at 3h 56m, compared with 5h 35m via Salt Lake City (SLC) and 6h 41m via Las Vegas Harry Reid Intl (LAS).

  • What is the time difference between Ontario and Denver?

    Denver is 1 hour ahead of Ontario (Mountain Time vs Pacific Time). Plan for the time shift when scheduling connections or first-day activities.

  • What popular places can I visit in Denver?

    Some of the most popular sights in Denver are Colorado Convention Center, Coors Field and Ball Arena. These are among the most viewed places in Denver on KAYAK.

  • Which airlines offer extra legroom and free seat selection on Ontario to Denver flights?

    Among airlines operating Ontario to Denver flights:

    • Frontier: offers free seat selection
    • Southwest: offers free seat selection
    • United Airlines: offers extra legroom; offers free seat selection

    Extra legroom and free seat selection availability depends on fare class and route.

  • Which airlines include bags at no extra cost on Ontario to Denver flights?

    Here are some options for this route, based on selected ticket types and cabin classes:

    • Frontier: a cabin bag and a checked bag in Economy Class
    • United Airlines: a cabin bag and a checked bag in Economy Class
    • Southwest: a cabin bag in Economy Class class

    Bag allowance can vary by ticket type, cabin class, route and airline, so always check the fare details before booking.

  • What are the transit options at Denver International Airport (DEN)?

    There is a large network of transit options that connect to Denver International Airport (DEN). You can use the airport rail serving the eight stations which runs regularly every 15min during the day and every 30min at night. Also, you can opt for ground transportation such as hotel shuttles, taxis, ride shares, and rental car shuttles. However, if you are in a hurry, the most convenient option is to use a taxi.

  • Can I exchange my foreign currency at Denver International Airport (DEN)?

    Denver International Airport (DEN) has three global money exchange locations. They are located in Gates A, B, and Jeppesen Terminal Level 5. You can also use the airport exchange kiosk, although they have the worst exchange rates.

  • What transportation option is available to Ontario Airport (ONT)?

    There are many ways you can get to Ontario Airport (ONT) from Ontario City Center. Public transits offer cheap and easy travel although takes longer to arrive at the airport. The station is right within ONT for easy passenger access. There is also the use of airport shuttles to provide transportation to passengers. Alternatively, you can use a taxi, which is the fastest way to get to the airport.

  • Are there nursing suites at Denver International Airport (DEN)?

    There are various options of nursing suites for passengers with kids at Denver International Airport (DEN). They are located at each of DEN’s concourses, offering excellent security and a peaceful environment to nurse after a long flight. Also, the suites are available throughout the day and night.

Your guide to booking Ontario to Denver flights

Get tips on when to book, when to fly and what to know before your trip.
  • If your dates are flexible, aim for a Wednesday departure and avoid flying on Sunday. On this route, Wednesday flights average $196, about $96 less than Sunday fares (33% savings) based on the last 12 months.
  • For the best chance at a low fare, aim to book around 7 weeks before you fly. On this route, that window historically saves about 49% versus last-minute pricing (KAYAK booking data, last 12 months).
  • If you can choose when to travel, plan your Ontario to Denver trip for February. Fares historically average $168 round-trip in that month - typically $161 less than the most expensive month, which is June (based on the last 12 months).
  • If you're arriving late at night and need somewhere to stay, check out these hotels close to Denver Intl Airport.

    • The Westin Denver International Airport
  • If you are flying out of Ontario Airport (ONT) and need to park, you will find various parking spots. There are long and short-term parking options depending on how long you want to park. The parking stalls are open throughout to every passenger who wishes to park offering the ultimate convenience. They are located in each terminal providing valet, premium, and general parking options.
  • When flying from Ontario Airport (ONT), it is recommended that you arrive at least 2h earlier before your scheduled flight. It is vital to consider the time you will take when checking in at the airport, getting boarding passes, and passing through security checks. Luckily, the Ontario Airport (ONT) waiting time is improving to excellent staffing and screening options.
  • There are multiple power stations in all terminals when you get to Denver International Airport (DEN) and need to work. The stations are well-equipped making it comfortable to work at your convenience.
  • With multiple lounges at Denver International Airport (DEN), passengers can take advantage of the services and refuel when waiting for the next flight or shuttle bus. All the lounges are easily accessible as they are located near passenger departures.
  • If you are having an early morning flight and looking for accommodation, there are various hotels near Ontario Airport (ONT) offering excellent services like free shuttle transfer to the airport. These hotels include Double Tree by Hilton Hotel located 0.9 miles from the airport and Holiday Inn Ontario Airport, which is around 0.7 miles from the airport.

Prefer to fly direct from Ontario to Denver?

 
Find which airlines fly direct from Ontario Airport to Denver Intl Airport, which days they fly and book direct flights.

Direct departures

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

Direct returns

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

More options for your flight from Ontario to Denver

Complete your trip to Denver with a hotel stay or car rental