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$66+ Cheap flights from Ontario (ONT) to Colorado

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 12/7. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — DEN
Dec 6 — Dec 131
Sat 12/6
Sat 12/13
1 adult, Economy
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Find flight deals from Ontario to Colorado

Cheapest flights from Ontario to Colorado
Explore the most affordable flight options available from Ontario to Colorado. Find the lowest fares from popular airlines and budget airlines, with prices last updated on November 6, 2025.

This CheapOair deal was found by Cheapflights users on 11/6. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/53:20 pmONT - DEN
Nonstop2h 20mFrontier
Mon 12/812:58 pmDEN - ONT
Nonstop2h 27mFrontier
Deal found 11/6$88
This Super.com deal was found by Cheapflights users on 11/5. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 11/3012:58 amONT - DEN
Nonstop2h 22mFrontier
Mon 12/812:58 pmDEN - ONT
Nonstop2h 27mFrontier
Deal found 11/5$91
This Super.com deal was found by Cheapflights users on 11/6. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/2112:58 amONT - DEN
Nonstop2h 22mFrontier
Sun 12/71:40 pmDEN - ONT
Nonstop2h 26mFrontier
Deal found 11/6$92
This CheapOair deal was found by Cheapflights users on 11/5. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 11/3012:58 amONT - DEN
Nonstop2h 22mFrontier
Fri 12/512:58 pmDEN - ONT
Nonstop2h 27mFrontier
Deal found 11/5$93
This Frontier deal was found by Cheapflights users on 11/6. 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 12/246:45 amONT - DEN
Nonstop2h 21mFrontier
Wed 12/3110:32 pmDEN - ONT
Nonstop2h 27mFrontier
Deal found 11/6$94
This Super.com deal was found by Cheapflights users on 11/6. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/1912:58 amONT - DEN
Nonstop2h 22mFrontier
Fri 11/2110:29 pmDEN - ONT
Nonstop2h 28mFrontier
Deal found 11/6$96
This Super.com deal was found by Cheapflights users on 11/6. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/2012:23 pmONT - DEN
Nonstop2h 29mFrontier
Sun 11/2310:29 pmDEN - ONT
Nonstop2h 28mFrontier
Deal found 11/6$97
This Frontier deal was found by Cheapflights users on 11/5. 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.
Fri 11/217:48 pmONT - DEN
Nonstop2h 27mFrontier
Fri 11/2810:29 pmDEN - ONT
Nonstop2h 28mFrontier
Deal found 11/5$98
This CheapOair deal was found by Cheapflights users on 11/6. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/46:15 amONT - DEN
1 stop20h 43mFrontier
Mon 12/812:58 pmDEN - ONT
Nonstop2h 27mFrontier
Deal found 11/6$99
This Mytrip deal was found by Cheapflights users on 11/4. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/66:15 amONT - DEN
1 stop20h 43mFrontier
Mon 12/812:58 pmDEN - ONT
Nonstop2h 27mFrontier
Deal found 11/4$100
This Super.com deal was found by Cheapflights users on 11/6. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/198:45 amONT - DEN
Nonstop2h 22mFrontier
Sat 11/2210:29 pmDEN - ONT
Nonstop2h 28mFrontier
Deal found 11/6$102
This Delta deal was found by Cheapflights users on 11/5. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/44:49 pmONT - COS
1 stop4h 36mDelta
Tue 12/96:00 pmCOS - ONT
1 stop6h 58mDelta
Deal found 11/5$234

Cheap flight deals from Ontario to Colorado

Keep the following information in mind while searching for Ontario to Colorado flight deals. Data was last updated November 6, 2025.

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$88
(CheapOair)

One-way from

$66
(CheapOair)

Popular in

June

Cheapest in

January

Average price

$204

Good round-trip deal

$182 or less

Good one-way deal

$109 or less
Provider with most accurate pricing for Los Angeles-Denver Intl flight deals.
Search Deals
Provider most trusted by Cheapflights users for Los Angeles-Denver Intl flights.
Search Deals
From Ontario to Colorado
Search Deals
One-way flight from Ontario to Colorado
Search Deals
Highest demand for flights based on searches. 9% potential increase in price ($20 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 November 2025
Search Deals
Price to beat on a round-trip flight from Ontario to Colorado.
Search Deals
Price to beat on a one-way flight from Ontario to Colorado.
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Ontario to Colorado 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 November 6, 2025.
Use the filters below to find and compare flights from Ontario to Colorado that are best for you.

Fly from

Ontario

Fly to

Colorado

Route

Depart

Return

Price

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Thu 11/20

12:23 pm-3:52 pm

Nonstop2h 29m

Denver Intl

Fri 11/21

10:29 pm-11:57 pm

Nonstop2h 28m

$96

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Wed 11/19

12:58 am-4:20 am

Nonstop2h 22m

Denver Intl

Tue 11/25

10:29 pm-11:57 pm

Nonstop2h 28m

$97

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 11/22

12:58 am-4:20 am

Nonstop2h 22m

Denver Intl

Mon 12/1

10:29 pm-11:57 pm

Nonstop2h 28m

$98

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 11/25

12:58 am-4:20 am

Nonstop2h 22m

Denver Intl

Mon 12/1

10:29 pm-11:57 pm

Nonstop2h 28m

$98

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Thu 11/27

12:23 pm-3:52 pm

Nonstop2h 29m

Denver Intl

Fri 11/28

10:29 pm-11:57 pm

Nonstop2h 28m

$98

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sun 11/23

12:58 am-4:20 am

Nonstop2h 22m

Denver Intl

Fri 11/28

10:29 pm-11:57 pm

Nonstop2h 28m

$98

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 11/22

12:58 am-4:20 am

Nonstop2h 22m

Denver Intl

Fri 11/28

10:29 pm-11:57 pm

Nonstop2h 28m

$98

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Thu 12/4

10:12 pm-12:30 pm

1 stop13h 18m

Denver Intl

Mon 12/8

10:37 pm-9:17 pm

1 stop23h 40m

$110

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Fri 12/5

6:15 am-12:47 pm

1 stop5h 32m

Denver Intl

Sun 12/7

1:40 pm-3:06 pm

Nonstop2h 26m

$112

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sun 11/23

12:58 am-4:20 am

Nonstop2h 22m

Denver Intl

Mon 12/1

10:08 am-2:26 pm

1 stop5h 18m

$121

Flights are sorted by cheapest round-trip flights first.

Deals found on 11/4

Showing 1-10 of 60 results
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Best time to book a flight from Ontario to Colorado

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

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

Currently, March is the cheapest month in which you can book a flight from Ontario to Colorado (average of $36). Flying from Ontario to Colorado in September is currently the most expensive (average of $76). 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 CO?

Find hourly flight availability from Ontario to Colorado. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated November 6, 2025.

It’s typically best to fly out from Ontario to Colorado in the afternoon. Doing so could potentially save you 38% on the flight price compared to flying in the evening, which is usually more expensive.

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

Use this chart to determine the cheapest time to fly round-trip from Ontario to Colorado. Price data was last updated on December 16, 2024.

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

Weekly flight availability from Ontario to Colorado

Explore weekly flight availability from Ontario to Colorado. 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 November 6, 2025.

The most flights from ONT to USCO are scheduled on a Thursday (11 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (2 on average).

Reviews of airlines servicing Colorado

Get insights into the airlines that provide service to Colorado. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Colorado. Reviews last updated November 6, 2025.
See what other customers who have flown with Southwest, Delta, and United Airlines from Ontario to Colorado have to say. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,241 reviews

Comfort

8.0

Overall

8.0

Crew

8.6

Boarding

8.1

Food

7.0

Entertainment

7.5

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Southwest
8.0
Very good
4,241 reviews
Southwest
8.0
Very good
4,241 reviews

Comfort

8.0

Overall

8.0

Crew

8.6

Boarding

8.1

Food

7.0

Entertainment

7.5

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Delta
7.9
Good
8,001 reviews
Southwest
8.0
Very good
4,241 reviews

Comfort

8.0

Overall

8.0

Crew

8.6

Boarding

8.1

Food

7.0

Entertainment

7.5

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
United Airlines
7.4
Good
9,007 reviews
Southwest
8.0
Very good
4,241 reviews

Comfort

8.0

Overall

8.0

Crew

8.6

Boarding

8.1

Food

7.0

Entertainment

7.5

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
American Airlines
7.2
Good
11,040 reviews
Southwest
8.0
Very good
4,241 reviews

Comfort

8.0

Overall

8.0

Crew

8.6

Boarding

8.1

Food

7.0

Entertainment

7.5

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Frontier
5.8
Fair
3,115 reviews
Southwest
8.0
Very good
4,241 reviews

Comfort

8.0

Overall

8.0

Crew

8.6

Boarding

8.1

Food

7.0

Entertainment

7.5

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.

Related info for your journey

Find useful and relevant information for your journey from Ontario to Colorado. 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 from for flights from Ontario to Colorado?

    Ontario (ONT), located 3.1 mi from the city center, is the airport you fly out of when you book flights from Ontario to Colorado.

  • How popular is this Ontario to Colorado flight route?

    The Ontario to Colorado flight path was viewed by 364 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 Colorado?

    Airlines like Frontier, Delta, and United Airlines fly from Ontario to Colorado in about 2h 29m. The time it takes to get you to your destination can typically vary by up to 5h 05m. The distance from Ontario to Colorado is about 817 mi. When browsing for deals, the options you’ll see will be for both nonstop flights and flights with stops.

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

    The cheapest airlines for a one-way flight from Ontario to Colorado are Frontier ($73), Southwest ($79), and United Airlines ($79).

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

    The most popular route from Ontario to Colorado is Ontario - Denver Intl. You may also consider Ontario - Colorado Springs or Ontario - Aspen Pitkin County.

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

    Looking for the most reliable airlines to get you to your destination on time? Our data shows these are most likely to get you from Ontario to Colorado on time: United Airlines (85%), Air Canada (81%), Southwest (79%).

  • What are the cheapest flights from Ontario to Colorado?

    Looking at all options, your cheapest flight can be booked for $75. While the most popular route (Ontario - Denver Intl) can be booked for $57 on average, our data indicates $735 when flying from Ontario to Colorado.

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

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

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

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

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

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

    Currently, March is the cheapest month in which you can book a flight from Ontario to Colorado (average of $36). Flying from Ontario to Colorado in September is currently the most expensive (average of $76). 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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Alternative routes for Ontario to Colorado

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Top 5 airlines flying from Ontario to Colorado

Discover the top 5 airlines that operate flights from Ontario to Colorado. 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 November 6, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$61Average$141FlexibilityNo cancel feeOn-time62%
DeltaCheapest$109Average$273FlexibilityNo cancel feeOn-timeN/A
SouthwestCheapest$118Average$312FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$133Average$380FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$268Average$386FlexibilityNo cancel feeOn-time71%

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