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

Southwest, United Airlines, and Delta 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 October 2026, 20 flights take off from Ontario and land in Denver each week. The most common flight departure day for this route is Fri, with 70% 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 2 per day as of October 2026. The most frequent departure time is 6:00, with 51% of daily flights leaving at midday.

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 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 stopovers. 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 required travel and health documents for your Denver Intl Airport trip may vary depending on your itinerary and personal circumstances. As a general rule, you should carry multiple documents, including a national ID card or driver's licence and a passport valid for six months after your intended arrival at Denver Intl Airport. We recommend that you seek guidance from your airline or a reliable third party such as IATA.

R1 100 Cheap Flights from Ontario to Denver in 2026/27

Find the cheapest flights from Ontario to Denver

Return

One-way

Last minute

Direct

Cheap return flights

Enter your travel dates to find the best prices.

20:31 - 0:58ONT Ontario-DEN Denver Intl

27h 27m1 stop San Francisco

22:52 - 0:14DEN Denver Intl-ONT Ontario

2h 22mdirect

R1 650Frontier

Sat, Nov 21 - Thu, Nov 26

6:45 - 10:06ONT Ontario-DEN Denver Intl

2h 21mdirect

22:52 - 0:14DEN Denver Intl-ONT Ontario

2h 22mdirect

R1 916Frontier

Sat, Nov 21 - Thu, Nov 26

11:20 - 14:30ONT Ontario-DEN Denver Intl

2h 10mdirect

20:15 - 21:45DEN Denver Intl-ONT Ontario

2h 30mdirect

R2 183Southwest

Sat, Dec 5 - Mon, Dec 7

5:00 - 8:21ONT Ontario-DEN Denver Intl

2h 21mdirect

19:35 - 21:00DEN Denver Intl-ONT Ontario

2h 25mdirect

R2 283United Airlines

Mon, Dec 21 - Fri, Dec 25

14:45 - 18:00ONT Ontario-DEN Denver Intl

2h 15mdirect

8:05 - 9:35DEN Denver Intl-ONT Ontario

2h 30mdirect

R2 399Southwest

Fri, Nov 20 - Thu, Nov 26

5:00 - 8:17ONT Ontario-DEN Denver Intl

2h 17mdirect

19:25 - 20:51DEN Denver Intl-ONT Ontario

2h 26mdirect

R2 516United Airlines

Sat, Nov 21 - Sat, Nov 21

20:31 - 0:58ONT Ontario-DEN Denver Intl

27h 27m1 stop San Francisco

6:42 - 12:48DEN Denver Intl-ONT Ontario

7h 06m1 stop Las Vegas Harry Reid Intl

R2 566Frontier

Sat, Nov 21 - Thu, Nov 26

17:00 - 22:25ONT Ontario-DEN Denver Intl

4h 25m1 stop Las Vegas Harry Reid Intl

5:35 - 9:20DEN Denver Intl-ONT Ontario

4h 45m1 stop Phoenix Sky Harbor Intl

R2 616Southwest

Thu, Dec 31 - Tue, Jan 5

9:15 - 16:00ONT Ontario-DEN Denver Intl

5h 45m2 stops Phoenix Sky Harbor Intl El Paso

5:45 - 9:25DEN Denver Intl-ONT Ontario

4h 40m1 stop Phoenix Sky Harbor Intl

R2 633Southwest

Sat, Jan 16 - Tue, Jan 19

17:00 - 22:25ONT Ontario-DEN Denver Intl

4h 25m1 stop Las Vegas Harry Reid Intl

14:15 - 20:20DEN Denver Intl-ONT Ontario

7h 05m2 stops Los Angeles San Jose

R2 699Southwest

Tue, Jan 5 - Tue, Jan 12

Cheap last-minute flights

Enter your travel dates to find the best prices.

17:07 - 23:49ONT Ontario-DEN Denver Intl

5h 42m1 stop Las Vegas Harry Reid Intl

10:40 - 16:38DEN Denver Intl-ONT Ontario

6h 58m1 stop Dallas/Fort Worth

R5 915Frontier

Wed, Nov 4 - Wed, Nov 11

6:30 - 9:51ONT Ontario-DEN Denver Intl

2h 21mdirect

10:40 - 16:38DEN Denver Intl-ONT Ontario

6h 58m1 stop Dallas/Fort Worth

R7 614Frontier

Wed, Nov 4 - Wed, Nov 11

6:30 - 9:51ONT Ontario-DEN Denver Intl

2h 21mdirect

9:10 - 10:35DEN Denver Intl-ONT Ontario

2h 25mdirect

R9 114Frontier

Wed, Nov 4 - Wed, Nov 11

13:32 - 16:45ONT Ontario-DEN Denver Intl

2h 13mdirect

11:20 - 15:33DEN Denver Intl-ONT Ontario

5h 13m1 stop San Francisco

R13 163United Airlines

Fri, Nov 6 - Wed, Nov 11

16:51 - 21:54ONT Ontario-DEN Denver Intl

4h 03m1 stop Phoenix Sky Harbor Intl

12:23 - 16:19DEN Denver Intl-ONT Ontario

4h 56m1 stop Phoenix Sky Harbor Intl

R13 813American Airlines

Mon, Nov 2 - Wed, Nov 4

5:00 - 8:17ONT Ontario-DEN Denver Intl

2h 17mdirect

11:15 - 12:33DEN Denver Intl-ONT Ontario

2h 18mdirect

R14 379United Airlines

Fri, Nov 6 - Mon, Nov 9

5:00 - 8:17ONT Ontario-DEN Denver Intl

2h 17mdirect

17:25 - 22:48DEN Denver Intl-ONT Ontario

6h 23m1 stop San Francisco

R14 546United Airlines

Fri, Nov 6 - Mon, Nov 9

5:00 - 11:10ONT Ontario-DEN Denver Intl

5h 10m2 stops Phoenix Sky Harbor Intl Colorado Springs

19:15 - 23:40DEN Denver Intl-ONT Ontario

5h 25m2 stops Salt Lake City Las Vegas Harry Reid Intl

R14 879Southwest

Thu, Nov 5 - Thu, Nov 5

16:25 - 0:40ONT Ontario-DEN Denver Intl

7h 15m1 stop Phoenix Sky Harbor Intl

12:23 - 16:19DEN Denver Intl-ONT Ontario

4h 56m1 stop Phoenix Sky Harbor Intl

R16 045American Airlines

Sun, Nov 1 - Tue, Nov 3

6:00 - 13:58ONT Ontario-DEN Denver Intl

6h 58m1 stop Seattle/Tacoma Intl

7:03 - 18:17DEN Denver Intl-ONT Ontario

12h 14m1 stop Seattle/Tacoma Intl

R16 062Alaska Airlines

Wed, Nov 4 - Sat, Nov 7

Save money when you book flights with momondo

Big names, great deals

Search 100s of travel sites to compare prices.

Filter for what you want

Free Wi-Fi? Stopover? Instantly customise your results.

Trusted and free

We’re completely free to use - no hidden charges or fees.

Price Alerts

Not ready to book? to track prices.

Search flight deals

Frontier flights from Ontario to Denver

Our best Frontier deals on Ontario to Denver flight tickets

Frontier

Nov 21

ONT20:31Ontario

27h 27m

1 stop

DEN0:58Denver Intl

Nov 26

DEN22:52Denver Intl

2h 22m

ONT0:14Ontario

R1 650

Frontier

Nov 21

ONT6:45Ontario

2h 21m

DEN10:06Denver Intl

Nov 26

DEN22:52Denver Intl

2h 22m

ONT0:14Ontario

R1 916

Frontier

Nov 21

ONT20:31Ontario

27h 27m

1 stop

DEN0:58Denver Intl

Nov 26

DEN6:42Denver Intl

7h 06m

1 stop

ONT12:48Ontario

R2 566

United Airlines flights from Ontario to Denver

Our best United Airlines deals on Ontario to Denver flight tickets

United Airlines

Dec 21

ONT5:00Ontario

2h 21m

DEN8:21Denver Intl

Dec 25

DEN19:35Denver Intl

2h 25m

ONT21:00Ontario

R2 283

United Airlines

Nov 21

ONT5:00Ontario

2h 17m

DEN8:17Denver Intl

Nov 21

DEN19:25Denver Intl

2h 26m

ONT20:51Ontario

R2 516

United Airlines

Dec 21

ONT5:00Ontario

2h 21m

DEN8:21Denver Intl

Dec 24

DEN19:35Denver Intl

2h 25m

ONT21:00Ontario

R2 982

Fly from

Fly to

Route

Depart

Return

Price

Cheapest return flight

OntarioDenver

ONT Ontario - DEN Denver Intl

ONTDEN

Ontario

Sat 21/11

20:31-0:58

1 stop27h 27m

Denver Intl

Thu 26/11

22:52-0:14

Nonstop2h 22m

R1 650

OntarioDenver

ONT Ontario - DEN Denver Intl

ONTDEN

Ontario

Sat 21/11

6:45-10:06

Nonstop2h 21m

Denver Intl

Thu 26/11

22:52-0:14

Nonstop2h 22m

R1 916

Fastest return journey

OntarioDenver

ONT Ontario - DEN Denver Intl

ONTDEN

Ontario

Sat 5/12

11:20-14:30

Nonstop2h 10m

Denver Intl

Mon 7/12

20:15-21:45

Nonstop2h 30m

R2 183

OntarioDenver

ONT Ontario - DEN Denver Intl

ONTDEN

Ontario

Mon 21/12

5:00-8:21

Nonstop2h 21m

Denver Intl

Fri 25/12

19:35-21:00

Nonstop2h 25m

R2 283

OntarioDenver

ONT Ontario - DEN Denver Intl

ONTDEN

Ontario

Fri 20/11

14:45-18:00

Nonstop2h 15m

Denver Intl

Thu 26/11

8:05-9:35

Nonstop2h 30m

R2 399

OntarioDenver

ONT Ontario - DEN Denver Intl

ONTDEN

Ontario

Sat 21/11

5:00-8:17

Nonstop2h 17m

Denver Intl

Sat 21/11

19:25-20:51

Nonstop2h 26m

R2 516

OntarioDenver

ONT Ontario - DEN Denver Intl

ONTDEN

Ontario

Sat 21/11

20:31-0:58

1 stop27h 27m

Denver Intl

Thu 26/11

6:42-12:48

1 stop7h 06m

R2 566

OntarioDenver

ONT Ontario - DEN Denver Intl

ONTDEN

Ontario

Thu 31/12

17:00-22:25

1 stop4h 25m

Denver Intl

Tue 5/1

5:35-9:20

1 stop4h 45m

R2 616

OntarioDenver

ONT Ontario - DEN Denver Intl

ONTDEN

Ontario

Sat 16/1

9:15-16:00

2 stops5h 45m

Denver Intl

Tue 19/1

5:45-9:25

1 stop4h 40m

R2 633

OntarioDenver

ONT Ontario - DEN Denver Intl

ONTDEN

Ontario

Tue 5/1

17:00-22:25

1 stop4h 25m

Denver Intl

Tue 12/1

14:15-20:20

2 stops7h 05m

R2 699

Flights are sorted by cheapest return flights first.

Showing 1-10 of 20 resultsSorted by cheapest first

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 typical price of a round-trip flight between Ontario and Denver?

Prices are currently low for flights on this route.

Typical prices usually range from R2 849 to R5 748.
The lowest price recently found on this route was R1 650.

What is the cheapest month to fly to Denver?

The cheapest month to fly to Denver from Ontario is in February. Flight prices, which tend to average around R2 783, are often lower during this time because this is during the off-season. If you don’t want to visit Denver in February, then you should wait until January to fly from Ontario, when ticket prices are also cheap, with an average price of R2 849.

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 from Ontario 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 R4 104 when searching weeks before you fly. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Denver from Ontario for as low as R3 149 on momondo.

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

There is only 1 cabin class available to choose from on Ontario to Denver 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 October 2026, prices for Ontario to Denver flights are approximately 36% more expensive 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 return 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	R1 100
Direct flights	Every day
Airports in Denver	1 airport

The best one-way flight to Denver from Ontario in the past 72 hours is R1 100. The best return flight deal from Ontario to Denver found on momondo in the last 72 hours is R1 650.

Direct flights go from Ontario to Denver every day.

There is 1 airport in Denver. From Ontario there are direct flights to Denver Intl (DEN).

Search flight deals

Frequently asked questions about flying from Ontario to Denver

How far is Ontario to Denver Intl by plane?
Ontario and Denver Intl are 1288,3 km apart from one another.
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 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 stopovers. 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 required travel and health documents for your Denver Intl Airport trip may vary depending on your itinerary and personal circumstances. As a general rule, you should carry multiple documents, including a national ID card or driver's licence and a passport valid for six months after your intended arrival at Denver Intl Airport. We recommend that you seek guidance from your airline or a reliable third party such as IATA.
What is the most popular plane model from Ontario to Denver?
Based on momondo bookings for this flight route, the most popular plane model on flight routes from Ontario to Denver is Airbus A320neo (12,14% of total bookings). The next most popular plane models are Airbus A321neo (11,58%), Boeing 737 MAX 8 (10,77%), and Airbus A321-100/200 (8,13%).

Black Hawk

Manitou Springs

Why use momondo?

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

momondo collates all your flight options in one place and lets you filter them to find the perfect flight from Ontario to Denver. momondo saves you time and could save you money on your trip.

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

momondo does allow users to show only those flights to Denver from Ontario which offer a flexible booking policy as well as other useful filters and features.

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

Once you have performed a search in the form on the page, momondo provides useful filters and insights. We can show you the cheapest days and times to fly as well as help filter your options to help you make an informed choice when booking flights to Denver from Ontario.

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

Price alerts on flights to Denver from Ontario are quick and easy to set up on momondo. Simply perform a search and select the price alert feature. It is as simple as that.