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$55+ 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 11/12. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — DEN
Aug 23 — Aug 301
Sat 8/23
Sat 8/30
1 adult, Economy
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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 August 18, 2025.

Round-trip from

$76
(Cheapflightsfares)

One-way from

$55
(Cheapflightsfares)

Popular in

June

Cheapest in

January

Average price

$188

Good round-trip deal

$161 or less

Good one-way deal

$129 or less
From Ontario to Colorado
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One-way flight from Ontario to Colorado
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Highest demand for flights based on searches. 10% potential increase in price ($22 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease ($4 potential savings vs. average RT price).
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Average for round-trip flights in August 2025
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Price to beat on a round-trip flight from Ontario to Colorado.
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Price to beat on a one-way flight from Ontario to Colorado.
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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 August 18, 2025.

This Cheapflightsfares deal was found by Cheapflights users on 8/15. 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.
Fri 9/198:59 pmONT - DEN
Nonstop2h 27mFrontier
Sun 9/216:00 amDEN - ONT
Nonstop2h 23mFrontier
Deal found 8/15$76
This Cheapflightsfares deal was found by Cheapflights users on 8/16. 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 9/312:59 amONT - DEN
Nonstop2h 18mFrontier
Mon 9/86:29 pmDEN - ONT
Nonstop2h 25mFrontier
Deal found 8/16$77
This CheapOair deal was found by Cheapflights users on 8/15. 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 9/58:59 pmONT - DEN
Nonstop2h 27mFrontier
Tue 9/96:29 pmDEN - ONT
Nonstop2h 25mFrontier
Deal found 8/15$78
This Cheapflightsfares deal was found by Cheapflights users on 8/17. 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.
Tue 9/168:59 pmONT - DEN
Nonstop2h 27mFrontier
Tue 9/236:29 pmDEN - ONT
Nonstop2h 25mFrontier
Deal found 8/17$79
This Frontier deal was found by Cheapflights users on 8/17. 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 10/86:53 amONT - DEN
Nonstop2h 25mFrontier
Sat 10/1110:29 pmDEN - ONT
Nonstop2h 21mFrontier
Deal found 8/17$80
This FlightHub deal was found by Cheapflights users on 8/16. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/1311:53 amONT - DEN
Nonstop2h 28mFrontier
Tue 10/1410:29 pmDEN - ONT
Nonstop2h 21mFrontier
Deal found 8/16$82
This FlightHub deal was found by Cheapflights users on 8/16. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/258:59 pmONT - DEN
Nonstop2h 27mFrontier
Mon 9/296:30 amDEN - ONT
Nonstop2h 23mFrontier
Deal found 8/16$85
This Cheapflightsfares deal was found by Cheapflights users on 8/17. 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.
Tue 10/147:04 amONT - DEN
Nonstop2h 27mFrontier
Wed 10/1510:29 pmDEN - ONT
Nonstop2h 21mFrontier
Deal found 8/17$86
This Frontier deal was found by Cheapflights users on 8/17. 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.
Sun 11/25:53 amONT - DEN
Nonstop2h 25mFrontier
Tue 11/410:29 pmDEN - ONT
Nonstop2h 21mFrontier
Deal found 8/17$88
This Mytrip deal was found by Cheapflights users on 8/17. 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 9/68:59 pmONT - DEN
Nonstop2h 27mFrontier
Wed 9/106:29 pmDEN - ONT
Nonstop2h 25mFrontier
Deal found 8/17$89
This Cheapflightsfares deal was found by Cheapflights users on 8/18. 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.
Tue 9/212:59 amONT - DEN
Nonstop2h 20mFrontier
Wed 9/176:29 pmDEN - ONT
Nonstop2h 25mFrontier
Deal found 8/18$90
This Delta deal was found by Cheapflights users on 8/17. 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.
Tue 9/234:40 pmONT - COS
1 stop4h 31mDelta
Mon 9/295:55 pmCOS - ONT
1 stop6h 47mDelta
Deal found 8/17$217

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 August 18, 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

Fri 9/19

8:59 pm-12:26 am

Nonstop2h 27m

Denver Intl

Sun 9/21

6:00 am-7:23 am

Nonstop2h 23m

$76

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Fri 10/24

11:53 am-3:21 pm

Nonstop2h 28m

Denver Intl

Sun 10/26

8:15 am-9:35 am

Nonstop2h 20m

$76

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Thu 9/4

3:43 pm-7:08 pm

Nonstop2h 25m

Denver Intl

Mon 9/8

6:00 am-7:23 am

Nonstop2h 23m

$77

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Wed 9/17

8:59 pm-12:26 am

Nonstop2h 27m

Denver Intl

Sat 9/20

6:29 pm-7:54 pm

Nonstop2h 25m

$77

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 9/27

8:59 pm-12:26 am

Nonstop2h 27m

Denver Intl

Mon 9/29

6:30 am-7:53 am

Nonstop2h 23m

$78

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sun 9/28

8:59 pm-12:26 am

Nonstop2h 27m

Denver Intl

Tue 9/30

6:29 pm-7:54 pm

Nonstop2h 25m

$78

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Mon 9/15

4:08 pm-7:31 pm

Nonstop2h 23m

Denver Intl

Wed 9/17

6:29 pm-7:54 pm

Nonstop2h 25m

$78

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Mon 11/3

4:05 pm-7:29 pm

Nonstop2h 24m

Denver Intl

Thu 11/6

10:29 pm-11:50 pm

Nonstop2h 21m

$78

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Thu 9/25

8:59 pm-12:26 am

Nonstop2h 27m

Denver Intl

Fri 9/26

6:30 am-7:53 am

Nonstop2h 23m

$78

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Thu 9/18

8:59 pm-12:26 am

Nonstop2h 27m

Denver Intl

Sat 9/20

6:29 pm-7:54 pm

Nonstop2h 25m

$78

Flights are sorted by cheapest round-trip flights first.

Deals found on 8/16

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, October is the cheapest month in which you can book a flight from Ontario to Colorado (average of $197). Flying from Ontario to Colorado in March is currently the most expensive (average of $278). 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 August 18, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Ontario to Colorado as you normally would.

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 August 18, 2025.

The most flights from ONT to USCO are scheduled on a Monday (13 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (1 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 August 18, 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
4,246 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Crew

8.6

Overall

8.0

Boarding

8.1

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
4,246 reviews
Southwest
8.0
Very good
4,246 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Crew

8.6

Overall

8.0

Boarding

8.1

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
8.0
Very good
7,981 reviews
Southwest
8.0
Very good
4,246 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Crew

8.6

Overall

8.0

Boarding

8.1

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
8,925 reviews
Southwest
8.0
Very good
4,246 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Crew

8.6

Overall

8.0

Boarding

8.1

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
10,000 reviews
Southwest
8.0
Very good
4,246 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Crew

8.6

Overall

8.0

Boarding

8.1

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
3,212 reviews
Southwest
8.0
Very good
4,246 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Crew

8.6

Overall

8.0

Boarding

8.1

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 347 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 and Delta fly from Ontario to Colorado in about 2h 27m. The time it takes to get you to your destination can typically vary by up to 2h 04m. 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 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 - Vail Eagle 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: Air Canada (69%), Southwest (68%), United Airlines (63%).

  • What are the cheapest flights from Ontario to Colorado?

    Looking at all options, your cheapest flight can be booked for $65. While the most popular route (Ontario - Denver Intl) can be booked for $57 on average our data indicates $719 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, October is the cheapest month in which you can book a flight from Ontario to Colorado (average of $197). Flying from Ontario to Colorado in March is currently the most expensive (average of $278). 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.

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Alternative routes for Ontario to Colorado

See prices for flight routes from nearby airports that may be better suited for you.
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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 August 18, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$57Average$133FlexibilityNo cancel feeOn-time62%
DeltaCheapest$109Average$292FlexibilityNo cancel feeOn-timeN/A
SouthwestCheapest$120Average$349FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$137Average$382FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$278Average$393FlexibilityNo cancel feeOn-time71%

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