HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Ontario

$33+ Cheap flights from Colorado to Ontario (ONT)

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 9/5. Fares are subject to change and may not be available on all flights or dates of travel.
DEN — ONT
Aug 23 — Aug 301
Sun 8/23
Sun 8/30
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Colorado to Ontario 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.

Cheap flight deals from Colorado to Ontario

Cheapest flights from Colorado to Ontario
Explore the most affordable flight options available from Colorado to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on July 24, 2026.

This Frontier deal was found by Cheapflights users on 7/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/219:15 am
DEN
-
ONT
Nonstop2h 28m
Frontier
Tue 11/36:15 am
ONT
-
DEN
Nonstop2h 26m
Frontier
Deal found 7/21$115
This Frontier deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/178:45 am
DEN
-
ONT
Nonstop2h 19m
Frontier
Thu 8/2710:49 am
ONT
-
DEN
Nonstop2h 21m
Frontier
Deal found 7/22$117
This Cheapflightsfares deal was found by Cheapflights users on 7/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/1410:34 pm
DEN
-
ONT
Nonstop2h 21m
Frontier
Fri 10/302:35 pm
ONT
-
DEN
Nonstop2h 22m
Frontier
Deal found 7/24$119
This Cheapflightsfares deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/712:32 pm
DEN
-
ONT
Nonstop2h 25m
Frontier
Mon 10/126:00 am
ONT
-
DEN
Nonstop2h 26m
Frontier
Deal found 7/22$123
This Kiwi.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/138:45 am
DEN
-
ONT
Nonstop2h 19m
Frontier
Mon 8/179:36 am
ONT
-
DEN
1 stop13h 22m
Frontier
Deal found 7/22$125
This Kiwi.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/187:00 am
DEN
-
ONT
1 stop13h 01m
Frontier
Sat 8/227:56 pm
ONT
-
DEN
Nonstop2h 25m
Frontier
Deal found 7/22$126
This Kiwi.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/1210:29 pm
DEN
-
ONT
Nonstop2h 21m
Frontier
Tue 8/183:13 pm
ONT
-
DEN
2 stops11h 35m
Frontier
Deal found 7/22$127
This Kiwi.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/1710:29 pm
DEN
-
ONT
2 stops16h 34m
Frontier
Sat 8/226:00 am
ONT
-
DEN
Nonstop2h 24m
Frontier
Deal found 7/22$128
This Cheapflightsfares deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/159:15 am
DEN
-
ONT
Nonstop2h 28m
Frontier
Mon 10/192:55 pm
ONT
-
DEN
Nonstop2h 22m
Frontier
Deal found 7/22$131
This Kiwi.com deal was found by Cheapflights users on 7/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/187:00 am
DEN
-
ONT
1 stop13h 01m
Frontier
Tue 8/256:00 am
ONT
-
DEN
Nonstop2h 24m
Frontier
Deal found 7/22$132
This Kiwi.com deal was found by Cheapflights users on 7/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/297:00 am
DEN
-
ONT
1 stop13h 01m
Frontier
Mon 8/316:00 am
ONT
-
DEN
Nonstop2h 24m
Frontier
Deal found 7/21$133
This American Airlines deal was found by Cheapflights users on 7/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/268:30 am
GJT
-
ONT
1 stop4h 33m
American Airlines
Fri 9/412:59 pm
ONT
-
GJT
1 stop4h 27m
American Airlines
Deal found 7/24$319

Find flight deals from Colorado to Ontario

Keep the following information in mind while searching for Colorado to Ontario flight deals. Data was last updated July 24, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$115
(Frontier)

One-way from

$33
(Cheapflightsfares)

Popular in

June

Cheapest in

February

Average price

$244

Good round-trip deal

$187 or less

Good one-way deal

$146 or less
Provider with most accurate pricing for Denver Intl-Los Angeles flight deals.
Search Deals
Provider most trusted by Cheapflights users for Denver Intl-Los Angeles flights.
Search Deals
From Colorado to Ontario
Search Deals
One-way flight from Colorado to Ontario
Search Deals
Highest demand for flights based on searches. 11% potential increase in price ($27 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($5 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in July 2026
Search Deals
Price to beat on a round-trip flight from Colorado to Ontario.
Search Deals
Price to beat on a one-way flight from Colorado to Ontario.
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Colorado to Ontario that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated July 24, 2026.
Use the filters below to find and compare flights from Colorado to Ontario that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

DenverOntario

DEN - ONT

DENONT

Denver Intl

Thu 9/24

6:20 am-10:20 am

1 stop5h 00m

Ontario

Mon 9/28

4:10 pm-11:10 pm

1 stop6h 00m

$177
Quickest round-trip

DenverOntario

DEN - ONT

DENONT

Denver Intl

Sat 9/5

7:30 pm-8:53 pm

Nonstop2h 23m

Ontario

Sun 9/6

5:00 am-8:21 am

Nonstop2h 21m

$242

DenverOntario

DEN - ONT

DENONT

Denver Intl

Mon 8/17

6:00 am-12:12 pm

1 stop7h 12m

Ontario

Mon 8/31

5:00 am-8:21 am

Nonstop2h 21m

$327

DenverOntario

DEN - ONT

DENONT

Denver Intl

Tue 9/22

3:04 pm-11:16 am

1 stop21h 12m

Ontario

Mon 9/28

4:27 pm-12:20 pm

2 stops18h 53m

$330

DenverOntario

DEN - ONT

DENONT

Denver Intl

Thu 9/17

7:30 pm-11:16 am

1 stop16h 46m

Ontario

Sun 9/20

4:27 pm-12:20 pm

2 stops18h 53m

$340

Colorado SpringsOntario

COS - ONT

COSONT

Colorado Springs

Tue 8/18

6:16 pm-11:34 pm

1 stop6h 18m

Ontario

Sat 8/22

5:05 pm-10:28 pm

1 stop4h 23m

$341

DenverOntario

DEN - ONT

DENONT

Denver Intl

Thu 8/13

10:15 am-3:05 pm

2 stops5h 50m

Ontario

Mon 8/17

4:00 pm-11:05 pm

1 stop6h 05m

$342

Colorado SpringsOntario

COS - ONT

COSONT

Colorado Springs

Sat 8/22

7:00 am-2:15 pm

2 stops8h 15m

Ontario

Sat 8/29

5:40 am-12:10 pm

1 stop5h 30m

$346

DenverOntario

DEN - ONT

DENONT

Denver Intl

Sat 9/5

12:55 pm-6:20 pm

2 stops6h 25m

Ontario

Mon 9/7

5:15 am-10:45 am

1 stop4h 30m

$351

Grand JunctionOntario

GJT - ONT

GJTONT

Grand Junction Regnl

Wed 8/26

11:19 am-8:01 pm

2 stops9h 42m

Ontario

Fri 9/4

5:00 am-12:38 pm

1 stop6h 38m

$354

Flights are sorted by cheapest round-trip flights first.

Deals found on 7/23

Showing 1-10 of 60 resultsSorted by cheapest first
1
2
3
...
6

Best time to book a flight from Colorado to Ontario

Have a flexible travel schedule? Discover the best time to fly to Ontario from Colorado 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 Colorado to Ontario

What is the cheapest month to book a flight from Colorado to Ontario?

Currently, August is the cheapest month in which you can book a flight from Colorado to Ontario (average of $156). Flying from Colorado to Ontario in June is currently the most expensive (average of $304). 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 CO to ONT?

Find hourly flight availability from Colorado to Ontario. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated July 24, 2026.

It’s optimal to fly from Colorado to Ontario in the evening. By choosing this option you can save up to 19% on the cost of your flight, compared to a flight at noon.

Weekly flight availability from Colorado to Ontario

Explore weekly flight availability from Colorado to Ontario. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated July 24, 2026.

The most flights from USCO to ONT are scheduled on a Monday (14 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (8 on average).

How much does it cost to fly round-trip from Colorado to Ontario?

Airfare is below average for this route at the moment.
Colorado to Ontario flights typically cost between $147 and $268 in October.
The cheapest round-trip price found within the last 5 days was $115 on Frontier (Oct 21-Nov 3).

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

To ensure you get the cheapest price possible for a flight from Colorado to Ontario, you should look to book at least 81 days in advance of your intended travel date. The price of your flight may increase if you delay and leave booking until a week or so before departure.

What is the cheapest day to fly from Colorado to Ontario?

Use this chart to determine the cheapest time to fly round-trip from Colorado to Ontario. Price data was last updated on July 18, 2026.

Travelers seeking maximum savings on their Colorado to Ontario flight should consider departing on Wednesday afternoons when fares are most often at their lowest. Monday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.

Related info for your journey

Find useful and relevant information for your journey from Colorado to Ontario. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly into for flights to Ontario from Colorado?

    If you book a flight to Ontario from Colorado, you will be flying to Ontario, which is the city’s only airport. Ontario (ONT) is located 3.1 mi from the center of Ontario.

  • How popular is this Colorado to Ontario flight route?

    The Colorado to Ontario flight path was viewed by 72 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 Colorado to Ontario?

    For as low as $242, Southwest can have you in Ontario from Colorado in 2h 23m. The distance between Colorado and Ontario is about 817 mi. Both multi-stop and nonstop flights can be found to your destination and back.

  • What are the cheapest airlines to fly from Colorado to Ontario one-way?

    The cheapest airlines for a one-way flight from Colorado to Ontario are Frontier ($36), United Airlines ($74), and Southwest ($78).

  • What are the most popular routes from Colorado to Ontario?

    While some choose either Colorado Springs - Ontario or Grand Junction Regnl - Ontario, Denver Intl - Ontario is the most popular route from Colorado to Ontario.

  • What are the most reliable airlines from Colorado to Ontario?

    No one likes to see their flight delayed. When booking a flight from Colorado to Ontario consider choosing Frontier (73%), Volaris (73%) or Air Canada (68%) as they are the most reliable in getting you off to your destination on time.

  • What are the cheapest flights from Colorado to Ontario?

    While on average a flight from Colorado to Ontario is generally $236, our data shows the cheapest flight currently is $46. When looking at the most popular route, (Denver Intl - Ontario), you can expect to pay $66 for that flight.

  • Can I find deals for flights from Colorado to Ontario that include hotel bookings?

    Yes. In addition to deals on Colorado to Ontario flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Colorado to Ontario?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Colorado to Ontario.

  • Can I find deals for business class flights from Colorado to Ontario?

    Yes. Cheapflights offers flight deals from Colorado to Ontario 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 Colorado to Ontario?

    Currently, August is the cheapest month in which you can book a flight from Colorado to Ontario (average of $156). Flying from Colorado to Ontario in June is currently the most expensive (average of $304). 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

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Colorado to Ontario

See prices for flight routes from nearby airports that may be better suited for you.
Newark to San Francisco flights
John F Kennedy Intl to San Francisco flights
LaGuardia to San Francisco flights
John F Kennedy Intl to Los Angeles flights
Newark to Los Angeles flights
Newark to Las Vegas flights
John F Kennedy Intl to Las Vegas flights
Los Angeles to Las Vegas flights
Seattle to Los Angeles flights
Seattle to Las Vegas flights
Dallas/Fort Worth to Los Angeles flights
San Francisco to Las Vegas flights
O'Hare Intl to Las Vegas flights
Hobby to Las Vegas flights
Dallas/Fort Worth to Las Vegas flights
Stewart to San Francisco flights
O'Hare Intl to Los Angeles flights
LaGuardia to Los Angeles flights
Atlanta to Las Vegas flights
Dulles Intl to Las Vegas flights
Detroit to Las Vegas flights
George Bush Intcntl to Las Vegas flights
John F Kennedy Intl to Ontario flights
Los Angeles to San Francisco flights
San Francisco to Los Angeles flights
LaGuardia to Las Vegas flights
San Francisco to Ontario flights
Boston to Las Vegas flights
Hobby to Los Angeles flights
Reagan-National to Los Angeles flights
Baltimore to Los Angeles flights
Dallas/Fort Worth to San Francisco flights
Baltimore to Las Vegas flights
Santa Ana to Las Vegas flights
Reagan-National to Las Vegas flights
Denver to Las Vegas flights
Seattle to Ontario flights
Seattle to San Francisco flights
San Francisco to Santa Ana flights
Boston to Los Angeles flights
Atlanta to Los Angeles flights
Santa Ana to San Francisco flights
Ontario to San Francisco flights
Newark to San Diego flights
Los Angeles to San Jose flights
Ontario to Las Vegas flights
Orlando to Las Vegas flights
George Bush Intcntl to Los Angeles flights
San Jose to Las Vegas flights
Boston to San Francisco flights

Top 5 airlines flying from Colorado to Ontario

Discover the top 5 airlines that operate flights from Colorado to Ontario. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated July 24, 2026.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$64Average$188FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$117Average$394FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$157Average$321FlexibilityNo cancel feeOn-time63%
DeltaCheapest$196Average$266FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$200Average$362FlexibilityNo cancel feeOn-time71%

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.