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Cheap flights from Ontario to Denver from £59

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 6/12. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — DEN
31 Aug — 7 Sep1
1 adult

Cheap flight deals from Ontario to Denver

Discover tips and strategies to find the most affordable flight options for your journey from Ontario (ONT) to Denver (DEN). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated 26 August 2025.

Round-trip from

£146

One-way from

£59

Popular in

June

Cheapest in

January

Average price

£128
Southwest
  • Southwest
  • 6/10-10/10
  • Nonstop
  • 4h 30m total
  • Ontario to Denver
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United Airlines
  • United Airlines
  • 6/12
  • Nonstop
  • 2h 13m total
  • Ontario to Denver
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Highest demand for flights based on searches. 17% potential increase in price (£17 potential increase over avg. return price).
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Cheapest flight prices on average. 4% potential price decrease (£4 potential savings vs. average return price).
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Average for round-trip flights in August 2025
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Find 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 26 August 2025.

Mon 6/1005:30ONT - DEN
Nonstop2h 15mSouthwest
Fri 10/1022:25DEN - ONT
Nonstop2h 15mSouthwest
Deal found 25/8£146
Tue 30/911:39ONT - DEN
1 stop7h 48mAlaska Airlines
Tue 7/1018:20DEN - ONT
1 stop6h 43mAlaska Airlines
Deal found 23/8£153
Mon 15/915:30ONT - DEN
Nonstop2h 15mSouthwest
Tue 16/920:45DEN - ONT
Nonstop2h 20mSouthwest
Deal found 25/8£153
Fri 14/1116:11ONT - DEN
1 stop6h 48mAlaska Airlines
Mon 17/1118:46DEN - ONT
1 stop6h 10mAlaska Airlines
Deal found 24/8£160
Sat 4/1009:50ONT - DEN
1 stop4h 00mDelta
Mon 6/1005:30DEN - ONT
1 stop4h 35mDelta
Deal found 25/8£161
Mon 29/911:50ONT - DEN
1 stop8h 52mDelta
Mon 6/1005:30DEN - ONT
1 stop4h 35mDelta
Deal found 23/8£168
Tue 9/911:39ONT - DEN
1 stop9h 23mAlaska Airlines
Tue 16/908:00DEN - ONT
1 stop7h 12mAlaska Airlines
Deal found 23/8£175
Fri 19/916:40ONT - DEN
1 stop5h 04mDelta
Tue 23/905:45DEN - ONT
1 stop4h 13mDelta
Deal found 25/8£176
Wed 5/1106:40ONT - DEN
2 stops6h 30mSouthwest
Sat 8/1107:45DEN - ONT
1 stop5h 25mSouthwest
Deal found 26/8£179
Sat 13/1205:05ONT - DEN
Nonstop2h 15mUnited Airlines
Mon 15/1211:15DEN - ONT
Nonstop2h 17mUnited Airlines
Deal found 25/8£183
Tue 21/1007:10ONT - DEN
2 stops13h 36mAlaska Airlines
Sat 25/1019:02DEN - ONT
1 stop5h 47mAlaska Airlines
Deal found 24/8£189
Tue 9/913:15ONT - DEN
1 stop5h 31mDelta
Sat 13/905:45DEN - ONT
1 stop4h 12mDelta
Deal found 24/8£190

Cheapflights Fare Finder

 
Customise your flight search to find flights from Ontario to Denver 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 858,174 searches. Data last updated 26 August 2025.
Use the filters below to find and compare flights from Ontario to Denver that are best for you.

Fly from

Ontario

Fly to

Denver

Route

Depart

Return

Price

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Mon 6/10

05:30-08:45

Nonstop2h 15m

Denver Intl

Fri 10/10

22:25-23:40

Nonstop2h 15m

£146

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 30/9

11:39-20:27

1 stop7h 48m

Denver Intl

Tue 7/10

18:20-00:03

1 stop6h 43m

£153

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Mon 15/9

15:30-18:45

Nonstop2h 15m

Denver Intl

Tue 16/9

20:45-22:05

Nonstop2h 20m

£153

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Fri 14/11

16:11-23:59

1 stop6h 48m

Denver Intl

Mon 17/11

18:46-23:56

1 stop6h 10m

£160

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Thu 2/10

11:50-21:42

1 stop8h 52m

Denver Intl

Sat 18/10

05:30-09:05

1 stop4h 35m

£161

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 30/9

13:15-19:43

1 stop5h 28m

Denver Intl

Mon 6/10

05:30-09:05

1 stop4h 35m

£161

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Wed 17/9

16:40-22:44

1 stop5h 04m

Denver Intl

Mon 29/9

05:45-08:57

1 stop4h 12m

£161

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 4/10

06:00-12:00

1 stop5h 00m

Denver Intl

Sat 4/10

18:25-22:41

1 stop5h 16m

£161

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 13/9

13:15-19:18

1 stop5h 03m

Denver Intl

Tue 16/9

05:45-08:58

1 stop4h 13m

£161

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Wed 24/9

11:50-21:42

1 stop8h 52m

Denver Intl

Mon 29/9

05:45-08:57

1 stop4h 12m

£161

Flights are sorted by cheapest return flights first.

Deals found on 24/8

Showing 1-10 of 21 results
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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 return 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

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

Use this chart to determine the optimal time to book a return flight from Ontario to Denver. Price data was last updated on 22 August 2025.

Booking 55 days in advance of your planned departure date is, on average, the best time to get cheap flights from Ontario to Denver. The general trend is that the closer you book to the departure date, the more expensive your flight will be.

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

Currently, January is the cheapest month in which you can book a flight from Ontario to Denver (average of £667). Flying from Ontario to Denver in July is currently the most expensive (average of £985). 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?

Find hourly flight availability from Ontario to Denver. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated 26 August 2025.

It’s optimal to fly from Ontario to Denver in the evening. By choosing this option you can save up to 85% on the cost of your flight, compared to a flight at midday.

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.

  • How popular is this Ontario to Denver flight route?

    The Ontario to Denver Intl flight path was viewed by 8 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?

    Departing from Ontario to Denver will take you 2h 15m. There are 817 mi between Ontario and Denver. When browsing for deals, the options you’ll see will be for both direct flights and flights with stops.

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

    The cheapet airlines for a one-way flight from Ontario to Denver are Hawaiian Airlines (£65), Alaska Airlines (£65), and Southwest (£73).

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

    Before booking your flight to Denver from Ontario, check out the most reliable airlines to get you to your destination on time: Air Canada (69%), Southwest (68%), United Airlines( 63%).

  • 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 holiday 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, January is the cheapest month in which you can book a flight from Ontario to Denver (average of £667). Flying from Ontario to Denver in July is currently the most expensive (average of £985). 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

Travelling to a place near Denver?

Book flights to Denver if you plan to visit one of these locations
Winter Park
Frisco

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Alternative routes for Ontario to Denver

See prices for flight routes from nearby airports that may be better suited for you.
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Fly with Cheapflights

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How does Cheapflights help users find flights from Ontario to Denver?

900+ travel sites are searched through when a user searches for a flight using Cheapflights. From the search interface, users can use filters to choose airlines, airports, flight times, cabin classes and more to their preference. Book your flight to Denver from Ontario today with Cheapflights!

Why should you use Cheapflights to find cheap flight tickets from Ontario to Denver?

Cheapflights helps you find that perfect flight to Denver from Ontario by searching from hundreds of airlines and agencies you know and love. We are also free to use, in case you were wondering!

Can Cheapflights find flights from Ontario to Denver with no change fees?

Cheapflights does show flights with no change fees to all users. To see these options for flights from Ontario to Denver, users can toggle the no change fees filter when performing a flight search.

Can Cheapflights notify me if prices for flights from Ontario to Denver become cheaper?

Not ready to book yet? You can track prices for flights from Ontario to Denver on Cheapflights with our Price Alert feature and get notified when better prices are available.

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