How popular is this Ontario to Denver flight route?

The Ontario to Denver Intl flight path was viewed by 346 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

How long is the flight from Ontario to Denver?

For as low as $110, Frontier can have you in Denver from Ontario in 2h 22m. The distance between Ontario and Denver is about 817 mi. Most flights are nonstop.

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 $117 and $127, respectively. These flights start at 64% 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 $35. Users have also found prices from $68 and $78 on Southwest and United Airlines, respectively.

Weekly flight availability from Ontario to Denver

The most flights from ONT to DEN are scheduled on a Thursday (9 on average). You will have fewer flight options on Friday, which is when the least amount of flights are scheduled (3 on average).

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.

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).

What are the cheapest flights from Ontario to Denver?

While on average a flight from Ontario to Denver is generally $605, our data shows the cheapest flight currently is $57. When looking at the most popular route, (Ontario - Denver Intl), you can expect to pay $47 for that flight.

What are the most reliable airlines from Ontario to Denver?

The top 3 most reliable airlines when flying from Ontario to Denver are Frontier (87%), Southwest (80%) and Air Canada (78%).

What are the most popular airlines that fly from Ontario to Denver?

The most popular airlines flying from Ontario to Denver are Frontier, Southwest and United Airlines. Something to consider prior to booking your flight.

Most accurate provider : When it comes to deals on Ontario-Denver flights, users find the pricing of CheapOair to be most consistent on Cheapflights vs. CheapOair Users can find the same prices on Ontario-Denver flight deals on Cheapflights vs. CheapOair >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 CheapOair the most. CheapOair 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.

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 10m for a nonstop flight. There are 5 flights from Ontario to Denver per day from 4 airlines.

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.

$45+ Flights from Ontario to Denver

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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.

Cheapflights Tip: The best prices from Ontario to Denver Intl are usually found in January or February, booked 88 days in advance, depart on a Friday or Thursday and return on a Wednesday

Cheap 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 December 12, 2025.

Wed 12/316:45 amONT - DEN

Nonstop2h 21mFrontier

Wed 1/79:45 pmDEN - ONT

Nonstop2h 29mFrontier

Deal found 12/10

$108

Mon 12/296:00 pmONT - DEN

1 stop8h 58mFrontier

Mon 1/1210:29 pmDEN - ONT

Nonstop2h 27mFrontier

Deal found 12/11

$121

Mon 12/296:00 pmONT - DEN

1 stop8h 58mFrontier

Fri 1/910:29 pmDEN - ONT

Nonstop2h 27mFrontier

Deal found 12/11

$125

Sun 12/216:37 pmONT - DEN

1 stop13h 27mFrontier

Wed 1/281:34 pmDEN - ONT

Nonstop2h 33mFrontier

Deal found 12/10

$135

Sun 12/216:00 amONT - DEN

1 stop26h 04mFrontier

Tue 1/68:45 pmDEN - ONT

Nonstop2h 27mFrontier

Deal found 12/10

$147

Tue 12/234:41 pmONT - DEN

1 stop6h 26mFrontier

Sat 1/36:21 pmDEN - ONT

1 stop6h 00mFrontier

Deal found 12/11

$163

Tue 12/234:41 pmONT - DEN

1 stop6h 26mFrontier

Sun 12/2810:37 pmDEN - ONT

1 stop23h 40mFrontier

Deal found 12/11

$164

Fri 12/265:54 pmONT - DEN

1 stop9h 04mFrontier

Wed 12/3110:37 pmDEN - ONT

1 stop19h 45mFrontier

Deal found 12/11

$165

Best flights from Ontario to Denver
Discover carefully curated flight deals from Ontario to Denver that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated December 12, 2025.

Wed 1/77:00 amONT - DEN

Nonstop2h 22mFrontier

Sat 1/109:50 pmDEN - ONT

1 stop10h 46mFrontier

Deal found 12/11

$110

Tue 1/65:55 amONT - DEN

1 stop4h 40mSouthwest

Tue 1/612:35 pmDEN - ONT

1 stop5h 20mSouthwest

Deal found 12/11

$177

Tue 1/134:03 pmONT - DEN

1 stop6h 32mAlaska Airlines

Thu 1/2211:49 amDEN - ONT

1 stop6h 14mAlaska Airlines

Deal found 12/11

$194

Tue 1/66:00 amONT - DEN

1 stop4h 54mDelta

Tue 1/66:23 pmDEN - ONT

1 stop5h 15mDelta

Deal found 12/10

$197

Sat 2/148:21 amONT - DEN

1 stop11h 12mFrontier

Tue 2/178:00 pmDEN - ONT

Nonstop2h 34mFrontier

Deal found 12/11

$110

Wed 1/77:00 amONT - DEN

Nonstop2h 22mFrontier

Fri 1/910:29 pmDEN - ONT

1 stop16h 57mFrontier

Deal found 12/11

$145

Mon 1/56:00 pmONT - DEN

1 stop4h 28mFrontier

Sat 1/109:45 pmDEN - ONT

Nonstop2h 29mFrontier

Deal found 12/11

$146

Sat 1/105:30 amONT - DEN

2 stops6h 30mSouthwest

Tue 1/138:35 amDEN - ONT

2 stops7h 05mSouthwest

Deal found 12/10

$205

Wed 1/2811:53 amONT - DEN

1 stop10h 42mAlaska Airlines

Sat 1/317:00 amDEN - ONT

2 stops11h 03mAlaska Airlines

Deal found 12/10

$206

Wed 1/2111:53 amONT - DEN

1 stop10h 42mAlaska Airlines

Wed 1/287:00 amDEN - ONT

2 stops13h 16mAlaska Airlines

Deal found 12/10

$206

Last-minute flights from Ontario to Denver
Discover last-minute flight deals from Ontario to Denver. Data last updated December 12, 2025 and is based on user searches.

Tue 1/67:00 amONT - DEN

Nonstop2h 22mFrontier

Tue 1/68:45 pmDEN - ONT

Nonstop2h 27mFrontier

Deal found 12/11

$92

Wed 1/77:00 amONT - DEN

Nonstop2h 22mFrontier

Sat 1/109:45 pmDEN - ONT

Nonstop2h 29mFrontier

Deal found 12/9

$103

Thu 1/86:00 amONT - DEN

Nonstop2h 26mFrontier

Sun 1/1110:29 pmDEN - ONT

Nonstop2h 27mFrontier

Deal found 12/11

$84

Fri 1/96:00 amONT - DEN

Nonstop2h 26mFrontier

Mon 1/1210:29 pmDEN - ONT

Nonstop2h 27mFrontier

Deal found 12/11

$85

Sun 1/116:00 amONT - DEN

Nonstop2h 26mFrontier

Fri 1/1610:29 pmDEN - ONT

Nonstop2h 30mFrontier

Deal found 12/11

$87

Sun 1/116:00 amONT - DEN

Nonstop2h 26mFrontier

Sun 1/1810:29 pmDEN - ONT

Nonstop2h 30mFrontier

Deal found 12/11

$88

Mon 1/1210:18 pmONT - DEN

1 stop11h 24mFrontier

Sat 1/179:20 pmDEN - ONT

Nonstop2h 39mFrontier

Deal found 12/11

$100

Tue 1/136:49 pmONT - DEN

1 stop14h 53mFrontier

Tue 1/201:34 pmDEN - ONT

Nonstop2h 33mFrontier

Deal found 12/11

$99

Tue 1/207:15 amONT - DEN

Nonstop2h 25mFrontier

Thu 1/297:00 amDEN - ONT

1 stop4h 32mFrontier

Deal found 12/11

$93

Thu 1/226:20 amONT - DEN

Nonstop2h 20mFrontier

Sun 1/2510:49 pmDEN - ONT

Nonstop2h 31mFrontier

Deal found 12/11

$83

Thu 1/226:20 amONT - DEN

Nonstop2h 20mFrontier

Sun 2/14:26 pmDEN - ONT

1 stop4h 06mFrontier

Deal found 12/11

$102

Sat 1/247:15 amONT - DEN

Nonstop2h 25mFrontier

Wed 1/289:44 pmDEN - ONT

1 stop13h 25mFrontier

Deal found 12/11

$94

One-way flights from Ontario to Denver
Search for one-way flight options from Ontario to Denver. Find affordable one-way fares based on user searches. Data last updated December 12, 2025.

Sun 2/226:00 amONT - DEN

Nonstop2h 26mFrontier

Deal found 12/10

$45

Fri 1/96:00 amONT - DEN

Nonstop2h 26mFrontier

Deal found 12/11

$63

Sun 1/255:57 pmONT - DEN

1 stop4h 23mFrontier

Deal found 12/11

$64

Wed 3/116:15 amONT - DEN

Nonstop2h 20mFrontier

Deal found 12/11

$65

Fri 3/66:15 amONT - DEN

Nonstop2h 20mFrontier

Deal found 12/11

$66

Mon 1/1210:18 pmONT - DEN

1 stop11h 24mFrontier

Deal found 12/11

$68

Sun 2/152:08 pmONT - DEN

Nonstop2h 23mFrontier

Deal found 12/11

$69

Wed 1/283:07 pmONT - DEN

1 stop16h 54mFrontier

Deal found 12/11

$70

Wed 2/253:22 pmONT - DEN

1 stop26h 12mFrontier

Deal found 12/11

$71

Sun 1/187:56 pmONT - DEN

1 stop10h 57mFrontier

Deal found 12/10

$73

Wed 1/710:45 amONT - DEN

1 stop6h 52mFrontier

Deal found 12/11

$75

Tue 12/234:41 pmONT - DEN

1 stop6h 26mFrontier

Deal found 12/11

$78

Find flight deals from Ontario to Denver

Most accurate provider	CheapOair 3 stars
Most trusted provider	CheapOair 3 stars
Round-trip from	$83 (Super.com)
One-way from	$45 (CheapOair)
Popular in	June
Cheapest in	January
Average price	$187
Good round-trip deal	$183 or less
Good one-way deal	$104 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. 10% potential increase in price ($18 potential increase over avg. RT price).

Search Deals

Cheapest flight prices on average. 3% potential price decrease ($6 potential savings vs. average RT price).

Search Deals

Average for round-trip flights in December 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

Fly from

Fly to

Route

Depart

Return

Price

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Wed 1/7

7:00 am-10:22 am

Nonstop2h 22m

Denver Intl

Sat 1/10

9:50 pm-7:36 am

1 stop10h 46m

$110

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 2/14

8:21 am-8:33 pm

1 stop11h 12m

Denver Intl

Tue 2/17

8:00 pm-9:34 pm

Nonstop2h 34m

$110

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Wed 1/7

7:00 am-10:22 am

Nonstop2h 22m

Denver Intl

Fri 1/9

10:29 pm-2:26 pm

1 stop16h 57m

$145

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Mon 1/5

6:00 pm-11:28 pm

1 stop4h 28m

Denver Intl

Sat 1/10

9:45 pm-11:14 pm

Nonstop2h 29m

$146

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 1/6

5:55 am-11:35 am

1 stop4h 40m

Denver Intl

Tue 1/6

12:35 pm-4:55 pm

1 stop5h 20m

$177

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 1/13

4:03 pm-11:35 pm

1 stop6h 32m

Denver Intl

Thu 1/22

11:49 am-5:03 pm

1 stop6h 14m

$194

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 1/6

6:00 am-11:54 am

1 stop4h 54m

Denver Intl

Tue 1/6

6:23 pm-10:38 pm

1 stop5h 15m

$197

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 1/10

5:30 am-1:00 pm

2 stops6h 30m

Denver Intl

Tue 1/13

8:35 am-2:40 pm

2 stops7h 05m

$205

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Wed 1/28

11:53 am-11:35 pm

1 stop10h 42m

Denver Intl

Sat 1/31

7:00 am-5:03 pm

2 stops11h 03m

$206

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Wed 1/21

11:53 am-11:35 pm

1 stop10h 42m

Denver Intl

Wed 1/28

7:00 am-7:16 pm

2 stops13h 16m

$206

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/11

Showing 1-10 of 20 results

Compare providers for flights from Ontario to Denver

Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Ontario to Denver in December.

Provider	Price Accuracy	Trust Score*
Expedia	Price Accuracy2 stars	Trust Score*3 stars
eDreams	Price Accuracy3 stars	Trust Score*3 stars
FlightHub	Price Accuracy3 stars	Trust Score*1 star
Cheapflightsfares	Price Accuracy3 stars	Trust Score*2 stars
CheapOair	Price Accuracy3 stars	Trust Score*3 stars
JustAirTicket	Price Accuracy-	Trust Score*1 star
Kiwi.com	Price Accuracy3 stars	Trust Score*3 stars
Justfly.com	Price Accuracy3 stars	Trust Score*3 stars
CheapTicketsDeal	Price Accuracy3 stars	Trust Score*3 stars
Priceline	Price Accuracy1 star	Trust 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 CheapOair to be most consistent on Cheapflights vs. CheapOair Users can find the same prices on Ontario-Denver flight deals on Cheapflights vs. CheapOair >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 CheapOair the most. CheapOair 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.

Cheapflights Insights

Everything you need to know about your flight from Ontario to Denver

Prices

Airlines

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

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, March is the cheapest month in which you can book a flight from Ontario to Denver (average of $36). Flying from Ontario to Denver in September is currently the most expensive (average of $75). 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?

It’s typically best to fly out from Ontario to Denver in the evening. Doing so could potentially save you 54% 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?

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

The best insider tips for Ontario to Denver flights

Cheapflights partnered with top experts to bring you the best recommendations for your Ontario to Denver trip

Airlines

Frontier

Frontier's UpFront Plus guarantees an empty middle seat in the front two rows.

Early check-in helps secure your place onboard due to frequent overbooking.

United Airlines

Basic Economy allows a personal item only; no carry-on bags are permitted.

Economy Plus offers extra legroom seats towards the front of the economy cabin.

Airports

ONT

ONT offers quick security with smoother lines than LAX, ideal for weekday business travelers. Consider reserving parking to ensure a spot during busy times.

DEN

Take the A Line train from DEN to Union Station for a cost-effective and efficient way to reach downtown Denver in 37 minutes.

Our travel experts

Marisa Garcia

Expert on Frontier

Harriet Baskas

Expert on United Airlines

Bill Fink

Expert on ONT

Emily Zemler

Expert on DEN

Reviews of airlines servicing Denver

Read through reviews of airlines operating flights from Ontario to Denver, such as Southwest, Delta, and United Airlines. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.

Southwest

7.9

Good

4,253 reviews

Reviews

1 / 20

2.0

Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

Southwest

7.9

Good

4,253 reviews

Southwest

7.9

Good

4,253 reviews

Reviews

1 / 20

2.0

Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

Delta

7.9

Good

8,005 reviews

Southwest

7.9

Good

4,253 reviews

Reviews

1 / 20

2.0

Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

United Airlines

7.4

Good

9,095 reviews

Southwest

7.9

Good

4,253 reviews

Reviews

1 / 20

2.0

Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

Frontier

5.8

Fair

3,084 reviews

Southwest

7.9

Good

4,253 reviews

Reviews

1 / 20

2.0

Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

Related info for your journey

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 10m for a nonstop flight. There are 5 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 346 users in the past month. Keep an eye out for changes in search interest prior to high and low season.
How long is the flight from Ontario to Denver?
For as low as $110, Frontier can have you in Denver from Ontario in 2h 22m. The distance between Ontario and Denver is about 817 mi. Most flights are nonstop.
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 $117 and $127, respectively. These flights start at 64% 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 $35. Users have also found prices from $68 and $78 on Southwest and United Airlines, respectively.
What are the most reliable airlines from Ontario to Denver?
The top 3 most reliable airlines when flying from Ontario to Denver are Frontier (87%), Southwest (80%) and Air Canada (78%).
What are the cheapest flights from Ontario to Denver?
While on average a flight from Ontario to Denver is generally $605, our data shows the cheapest flight currently is $57. When looking at the most popular route, (Ontario - Denver Intl), you can expect to pay $47 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, March is the cheapest month in which you can book a flight from Ontario to Denver (average of $36). Flying from Ontario to Denver in September is currently the most expensive (average of $75). 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

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Greeley

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Parker

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Complete your trip

Denver car rentals

Denver Intl Airport car rentals

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Other flights to Denver

Top 4 airlines flying from Ontario to Denver

Airline	Cheapest	Average	Flexibility	On-time
Frontier	Cheapest$59	Average$145	FlexibilityNo cancel fee	On-time62%
Southwest	Cheapest$117	Average$261	FlexibilityNo cancel fee	On-time63%
United Airlines	Cheapest$132	Average$276	FlexibilityNo cancel fee	On-time69%
Delta	Cheapest$236	Average$257	FlexibilityNo cancel fee	On-timeN/A

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$45+ 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 2/22. Fares are subject to change and may not be available on all flights or dates of travel.

Find cheap flights from Ontario to Denver with Cheapflights

1. Tell us where you want to go

2. Select your favorite providers

3. Compare prices and book

Cheapflights Tip: The best prices from Ontario to Denver Intl are usually found in January or February, booked 88 days in advance, depart on a Friday or Thursday and return on a Wednesday

Cheap flight deals from Ontario to Denver

Cheapest flights from Ontario to DenverExplore 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 December 12, 2025.

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 December 12, 2025.

Find flight deals from Ontario to Denver

Most accurate provider

Most trusted provider

Round-trip from

One-way from

Popular in

Cheapest in

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Airlines

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United Airlines

Airports

ONT

DEN

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Reviews of airlines servicing Denver

Read through reviews of airlines operating flights from Ontario to Denver, such as Southwest, Delta, and United Airlines. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.

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.

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Alternative routes for Ontario to Denver

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Top 4 airlines flying from Ontario to Denver

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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 December 12, 2025.