Cheap flights from Ontario to Denver from $48

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from Ontario to Denver departing on 10/21. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
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0 bags

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Cheap round-trip flights

Frontier Logo
12:59 am - 4:20 amONT-DEN
2h 21mnonstop
Frontier Logo
10:29 pm - 11:50 pmDEN-ONT
2h 21mnonstop
$97Frontier
Find Deal
Fri, Oct 24 - Tue, Oct 28
Frontier Logo
12:59 am - 4:19 amONT-DEN
2h 20mnonstop
Frontier Logo
7:25 am - 8:45 amDEN-ONT
2h 20mnonstop
$104Frontier
Find Deal
Wed, Aug 20 - Thu, Aug 21
Frontier Logo
12:59 am - 4:19 amONT-DEN
2h 20mnonstop
Frontier Logo
7:49 am - 9:09 amDEN-ONT
2h 20mnonstop
$107Frontier
Find Deal
Tue, Aug 5 - Sat, Aug 9
Frontier Logo
12:59 am - 4:19 amONT-DEN
2h 20mnonstop
Frontier Logo
7:49 am - 9:09 amDEN-ONT
2h 20mnonstop
$108Frontier
Find Deal
Tue, Aug 12 - Sat, Aug 16
Frontier Logo
12:59 am - 4:19 amONT-DEN
2h 20mnonstop
Frontier Logo
10:29 pm - 11:50 pmDEN-ONT
2h 21mnonstop
$109Frontier
Find Deal
Thu, Aug 14 - Sun, Aug 17
Frontier Logo
5:21 pm - 8:44 pmONT-DEN
2h 23mnonstop
Frontier Logo
10:29 pm - 11:50 pmDEN-ONT
2h 21mnonstop
$110Frontier
Find Deal
Thu, Aug 14 - Thu, Aug 21
Frontier Logo
12:59 am - 4:19 amONT-DEN
2h 20mnonstop
Frontier Logo
10:29 pm - 11:50 pmDEN-ONT
2h 21mnonstop
$112Frontier
Find Deal
Fri, Aug 22 - Sat, Aug 23
Frontier Logo
12:59 am - 4:19 amONT-DEN
2h 20mnonstop
Frontier Logo
10:29 pm - 11:50 pmDEN-ONT
2h 21mnonstop
$113Frontier
Find Deal
Thu, Aug 7 - Sun, Aug 10
Frontier Logo
12:59 am - 4:19 amONT-DEN
2h 20mnonstop
Frontier Logo
10:29 pm - 11:50 pmDEN-ONT
2h 21mnonstop
$114Frontier
Find Deal
Tue, Aug 26 - Wed, Sep 3
United Airlines Logo
5:10 am - 8:27 amONT-DEN
2h 17mnonstop
United Airlines Logo
7:25 pm - 8:43 pmDEN-ONT
2h 18mnonstop
$157United Airlines
Find Deal
Tue, Aug 19 - Tue, Aug 19

Frontier flights from Ontario to Denver

Our best Frontier deals on Ontario to Denver flight tickets
Frontier
Oct 24
ONT12:59 amOntario
2h 21m
DEN4:20 amDenver Intl
Oct 28
DEN10:29 pmDenver Intl
2h 21m
ONT11:50 pmOntario
Frontier
Aug 20
ONT12:59 amOntario
2h 20m
DEN4:19 amDenver Intl
Aug 21
DEN7:25 amDenver Intl
2h 20m
ONT8:45 amOntario
Frontier
Aug 5
ONT12:59 amOntario
2h 20m
DEN4:19 amDenver Intl
Aug 9
DEN7:49 amDenver Intl
2h 20m
ONT9:09 amOntario

See travel insights to Denver from

How to get the cheapest flight ticket from Ontario to Denver

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

What is the cheapest month to fly to Denver?

The cheapest month to fly to Denver from Ontario is in January. Flight prices, which tend to average around $98, are often lower during this time because this is during the off-season. If you don’t want to visit Denver in January, then you should wait until February to fly from Ontario, when ticket prices are also cheap, with an average price of $108.

What is the cheapest day to depart on your flight to Denver?

The cheapest day to depart on your flight to Denver is on a Saturday when prices can be found for as low as $238. This is often the case because there is less demand to fly during this day of the week. The most expensive day to fly to Denver is Sunday, with ticket prices averaging around $312.

What is the cheapest time of day to depart on your flight to Denver?

The cheapest time of day to fly to Denver is in the afternoon when flights can be purchased for as low as $218. Flights at noon are often more expensive with an average ticket price of $293.

What is the cheapest Ontario to Denver Intl flight route?

Fly from Ontario to Denver Intl for the best Ontario - Denver Intl flight prices

How far in advance should I book a flight to Denver?

You are more likely to see cheaper flights to Denver from Ontario when booking weeks ahead of your departure date. In general, you can expect to find flights to Denver for around $151 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Denver from Ontario for as low as $121 on momondo.

What cabin class options are available on Ontario to Denver Intl flights?

There are 4 cabin classes available to choose from on Ontario to Denver Intl flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

How have Ontario to Denver flight prices changed over time?

As of July 2025, prices for Ontario to Denver flights are approximately 6% cheaper when compared to flights at the same time last year.

When to book flights from Ontario to Denver

Are you open to changing your travel dates? Check out the ideal times to fly from Ontario to Denver according to our flight data. Find out which month and days have the cheapest flights.
Estimated round-trip price

Cheap Ontario to Denver (ONT to DEN) flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Ontario to Denver

Best Price Found

$48

Fastest flight time

2h 12m

Direct flights

Every day

Airports in Denver

1 airport
The best one-way flight to Denver from Ontario in the past 72 hours is $48. The best round-trip flight deal from Ontario to Denver found on momondo in the last 72 hours is $97.
The fastest flight from Ontario to Denver takes 2h 12m
Direct flights go from Ontario to Denver every day.
There is 1 airport near Denver: Denver Intl (DEN)

  • How far is Ontario to Denver Intl by plane?

    The straight-line distance from Ontario to Denver Intl is 800.5 mi. A reasonable flight in good conditions will take 2h 17m.

  • When did momondo last update prices for flights from Ontario Airport to Denver Intl Airport?

    Prices for flights from Ontario Airport to Denver Intl Airport were last updated today.

  • How many operators does momondo search for flights from Ontario Airport to Denver Intl Airport?

  • How old do you have to be to fly from Ontario Airport to Denver Intl Airport?

    The minimum age for a child to fly alone is five, but airlines offering an unaccompanied minor (UNMR) service may have their age restrictions, such as regulations concerning flight duration, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Ontario Airport to Denver Intl Airport.

  • What documentation or ID do you need to fly to Denver Intl Airport?

    The travel and health documents required for your trip to Denver Intl Airport can vary based on your itinerary and personal situation. As a rule, consider having multiple documents such as a national ID card or driver’s license, and a passport valid for six-months after you plan to arrive at Denver Intl Airport. We always recommend checking with your airline or a trusted third party such as IATA to get advice.

  • What is the most popular plane model from Ontario to Denver?

  • What is the most popular airline from Ontario to Denver?


Best airlines flying from Ontario to Denver

Compare and see reviews for airlines that fly from Ontario to Denver with momondo
Airline
Rating
Free Cancellation
Price
FrontierPriceFrom $54Free CancellationRating
5.9
3,261 reviews
Search Frontier flights
SouthwestPriceFrom $112Free CancellationRating
8.0
4,244 reviews
Search Southwest flights
United AirlinesPriceFrom $132Free CancellationRating
7.4
8,858 reviews
Search United Airlines flights
DeltaPriceFrom $159Free CancellationRating
8.0
7,956 reviews
Search Delta flights
  • Southwest Flights From Ontario to Denver

    Southwest flies from Ontario to Denver around 23 times per week, with 4,243 momondo users rating the airline 8.0/10. The cheapest Southwest deal from Ontario to Denver in the last 72 hours was $112 (round-trip), much lower than the average airfare cost of $260 for Southwest flights on this route.

  • United Airlines Flights From Ontario to Denver

    Another popular option for Ontario to Denver flights is United Airlines (7.4/10, 8,856 ratings). United Airlines flies from Ontario to Denver around 18 times per week, with deals starting from $132 round-trip and rising to an average price of around $273.


Traveling to a place near Denver?

Book flights to Denver if you plan to visit one of these locations
Estes Park
Breckenridge
Black Hawk
Aurora
Fort Collins
Keystone
Cripple Creek
Longmont
Boulder
Lakewood
Manitou Springs
Greeley
Westminster
Thornton
Winter Park
Silverthorne
Copper Mountain
Grand Lake
Golden
Frisco

Why use momondo?

Why should I use momondo to find a flight deal from Ontario to Denver?

Finding the right flight to Denver from Ontario is quick and easy when you have a range of options in front of you, from reputable agents and recognisable airlines. Options that can then be filtered down to find the best fit. That is what momondo does. We make finding flights to Denver quick and easy, saving you time and money.

Can I find flights from Ontario to Denver with flexible booking policies on momondo?

Yes. momondo allows you to filter the results for Ontario to Denver flights to just show those with flexible booking policies.

How can momondo help me find flights from Ontario to Denver?

momondo offers useful filters to help you find the right flight. Choose specific flight times, airports or even what payment method you prefer. We have numerous options to help you book your ideal flight from Ontario to Denver.

I’m not ready to book a flight from Ontario to Denver right now. Can momondo alert me if prices change?

If you are simply researching potential flights to Denver, momondo offers a useful price alert feature which will track prices for flights to Denver from Ontario and alert you when they change.


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1 adult
Sat 7/19
Sat 7/26

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