What is the cheapest airline that flies from Ontario to Denver Intl?

Frontier, Southwest, and American Airlines are the most popular carriers operating from Ontario to Denver Intl

How many flights depart from Ontario to Denver on average per week?

As of July 2025, 66 flights take off from Ontario and land in Denver each week. The most common flight departure day for this route is Thu, with 20% of weekly flights taking off on this day.

How many flights depart from Ontario to Denver on average per day?

The number of flights available between Ontario and Denver is 9 per day as of July 2025. The most frequent departure time is 5:00AM, with 44% of daily flights leaving in the afternoon.

What airlines fly to Denver?

Frontier, United Airlines and Southwest are the top three most popular airlines that fly to Denver from Ontario according to our data. Frontier is the first choice among our users, with 53% of people opting to fly with this airline when traveling to Denver. Keep in mind that there are 6 different airlines that fly to Denver on a routine basis, so you have a few additional options to choose from.

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?

The number of operators available for flights from Ontario Airport to Denver Intl Airport is 4 as of July 2025.

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.

$39 Cheap Flights from Ontario to Denver in 2025

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Find the cheapest flights from Ontario to Denver

Round-trip

One-way

Last minute

Direct

Cheap round-trip flights

8:59 pm - 12:26 amONT-DEN

2h 27mnonstop

6:29 pm - 7:54 pmDEN-ONT

2h 25mnonstop

$78Frontier

Find Deal

Fri, Sep 5 - Mon, Sep 8

12:59 am - 4:19 amONT-DEN

2h 20mnonstop

10:29 pm - 11:50 pmDEN-ONT

2h 21mnonstop

$79Frontier

Find Deal

Mon, Aug 18 - Sat, Aug 23

8:59 pm - 12:26 amONT-DEN

2h 27mnonstop

6:29 pm - 7:54 pmDEN-ONT

2h 25mnonstop

$81Frontier

Find Deal

Fri, Sep 5 - Tue, Sep 9

12:59 am - 4:20 amONT-DEN

2h 21mnonstop

10:29 pm - 11:50 pmDEN-ONT

2h 21mnonstop

$87Frontier

Find Deal

Fri, Oct 10 - Tue, Oct 14

12:59 am - 4:20 amONT-DEN

2h 21mnonstop

10:29 pm - 11:50 pmDEN-ONT

2h 21mnonstop

$91Frontier

Find Deal

Fri, Oct 24 - Tue, Oct 28

12:59 am - 4:19 amONT-DEN

2h 20mnonstop

10:29 pm - 11:50 pmDEN-ONT

2h 21mnonstop

$94Frontier

Find Deal

Tue, Jul 22 - Wed, Jul 30

12:59 am - 4:19 amONT-DEN

2h 20mnonstop

10:29 pm - 11:50 pmDEN-ONT

2h 21mnonstop

$95Frontier

Find Deal

Mon, Jul 28 - Sat, Aug 2

12:59 am - 4:20 amONT-DEN

2h 21mnonstop

10:29 pm - 11:50 pmDEN-ONT

2h 21mnonstop

$97Frontier

Find Deal

Fri, Oct 10 - Tue, Oct 14

8:59 pm - 12:26 amONT-DEN

2h 27mnonstop

6:29 pm - 7:54 pmDEN-ONT

2h 25mnonstop

$98Frontier

Find Deal

Sat, Sep 6 - Mon, Sep 8

2:45 pm - 6:00 pmONT-DEN

2h 15mnonstop

9:40 am - 11:00 amDEN-ONT

2h 20mnonstop

$132Southwest

Find Deal

Wed, Sep 3 - Sat, Sep 6

Frontier flights from Ontario to Denver

Our best Frontier deals on Ontario to Denver flight tickets

Frontier

Sep 5

ONT8:59 pmOntario

2h 27m

DEN12:26 amDenver Intl

Sep 8

DEN6:29 pmDenver Intl

2h 25m

ONT7:54 pmOntario

$78

Find similar

Frontier

Aug 18

ONT12:59 amOntario

2h 20m

DEN4:19 amDenver Intl

Aug 23

DEN10:29 pmDenver Intl

2h 21m

ONT11:50 pmOntario

$79

Find similar

Frontier

Sep 5

ONT8:59 pmOntario

2h 27m

DEN12:26 amDenver Intl

Sep 9

DEN6:29 pmDenver Intl

2h 25m

ONT7:54 pmOntario

$81

Find similar

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

Prices

Airlines

Other information

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 $235. 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 $316.

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 $148 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 27% 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	$39
Fastest flight time	2h 10m
Direct flights	Every day
Airports in Denver	1 airport

The best one-way flight to Denver from Ontario in the past 72 hours is $39. The best round-trip flight deal from Ontario to Denver found on momondo in the last 72 hours is $78.

The fastest flight from Ontario to Denver takes 2h 10m

Direct flights go from Ontario to Denver every day.

There is 1 airport near Denver: Denver Intl (DEN)

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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 15m.
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?
The number of operators available for flights from Ontario Airport to Denver Intl Airport is 4 as of July 2025.
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?
Based on momondo bookings for flights between Ontario and Denver, the leading plane model is Airbus A320neo, making up 13.48% of the total bookings. Other popular models include Airbus A321neo with 11.65%, Boeing 737 MAX 8 with 11.26%, and Airbus A319 with 10.86%.
What is the most popular airline from Ontario to Denver?
Based on momondo bookings for this flight route, the most popular airline on flight routes from Ontario to Denver is Frontier (73% of total bookings). The next most popular airlines are United Airlines (15%), Southwest (11%), and Delta (0%).

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
Frontier	PriceFrom $54	Free Cancellation	Rating 5.9 3,271 reviews	Search Frontier flights
Southwest	PriceFrom $112	Free Cancellation	Rating 8.0 4,249 reviews	Search Southwest flights
United Airlines	PriceFrom $132	Free Cancellation	Rating 7.4 8,846 reviews	Search United Airlines flights
Delta	PriceFrom $159	Free Cancellation	Rating 8.0 7,951 reviews	Search Delta flights

Southwest Flights From Ontario to Denver
Southwest flies from Ontario to Denver around 23 times per week, with 4,250 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, 8,846 ratings). United Airlines flies from Ontario to Denver around 13 times per week, with deals starting from $132 round-trip and rising to an average price of around $273.

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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Cheap flights from Ontario to Denver from $39

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 7/29. 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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Find the cheapest flights from Ontario to Denver

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Frontier flights from Ontario to Denver

Our best Frontier deals on Ontario to Denver flight tickets

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?

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 $235. 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 $316.

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?

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 27% cheaper when compared to flights at the same time last year.

What is the cheapest airline that flies from Ontario to Denver Intl?

Frontier, Southwest, and American Airlines are the most popular carriers operating from Ontario to Denver Intl

What airlines fly to Denver?

How many flights depart from Ontario to Denver on average per day?

The number of flights available between Ontario and Denver is 9 per day as of July 2025. The most frequent departure time is 5:00AM, with 44% of daily flights leaving in the afternoon.

How many flights depart from Ontario to Denver on average per week?

As of July 2025, 66 flights take off from Ontario and land in Denver each week. The most common flight departure day for this route is Thu, with 20% of weekly flights taking off on this day.

When to book flights from Ontario to Denver

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

Fastest flight time

Direct flights

Airports in Denver

How far is Ontario to Denver Intl by plane?

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

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?

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

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

Southwest Flights From Ontario to Denver

United Airlines Flights From Ontario to Denver

Traveling to a place near Denver?

Why use momondo?

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

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

How can momondo help me find flights 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?

An easier way to manage your Denver trip

We make it super easy to schedule, organize and travel with friends or family. Trips is free — and available to use no matter where you book.

Get notified when prices go down

Daily price changes in your inbox - only with Price Alerts.

Find better results for your trip to the United States

Airports servicing Colorado