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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 10/1. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — DEN
7 Jan — 14 Jan1
1 adult
1 adult, Economy, 0 bags

Cheap flight deals from Ontario to Denver

Enter your travel dates to find the best prices.

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 8 December 2025.

Sun 14/1205:05ONT - DEN
Nonstop2h 15mUnited Airlines
Sun 14/1219:20DEN - ONT
Nonstop2h 22mUnited Airlines
Deal found 6/12£275
Wed 31/1206:00ONT - DEN
1 stop16h 59mAlaska Airlines
Wed 7/107:00DEN - ONT
2 stops11h 03mAlaska Airlines
Deal found 5/12£280
Sun 21/1205:30ONT - DEN
2 stops6h 00mSouthwest
Wed 28/110:05DEN - ONT
2 stops7h 20mSouthwest
Deal found 7/12£286
Sun 14/1206:00ONT - DEN
1 stop4h 09mDelta
Sun 14/1218:22DEN - ONT
1 stop6h 36mDelta
Deal found 6/12£290
Mon 15/1212:40ONT - DEN
1 stop9h 41mDelta
Tue 30/1218:27DEN - ONT
1 stop6h 27mDelta
Deal found 7/12£318
Sun 28/1205:55ONT - DEN
Nonstop2h 15mSouthwest
Mon 5/122:45DEN - ONT
Nonstop2h 20mSouthwest
Deal found 6/12£322
Fri 12/1205:05ONT - DEN
Nonstop2h 15mUnited Airlines
Sun 14/1219:20DEN - ONT
Nonstop2h 22mUnited Airlines
Deal found 5/12£328
Sat 27/1205:05ONT - DEN
Nonstop2h 19mUnited Airlines
Tue 30/1211:15DEN - ONT
Nonstop2h 23mUnited Airlines
Deal found 6/12£331
Sun 14/1206:00ONT - DEN
1 stop4h 45mSouthwest
Sun 14/1215:30DEN - ONT
2 stops6h 05mSouthwest
Deal found 6/12£331
Thu 25/1216:36ONT - DEN
1 stop6h 23mAlaska Airlines
Wed 31/1207:20DEN - ONT
1 stop17h 39mAlaska Airlines
Deal found 7/12£334
Mon 15/1206:00ONT - DEN
1 stop4h 09mDelta
Fri 26/1218:27DEN - ONT
1 stop6h 27mDelta
Deal found 7/12£343
Wed 31/1208:40ONT - DEN
2 stops5h 30mSouthwest
Sun 4/117:15DEN - ONT
2 stops5h 45mSouthwest
Deal found 8/12£353

Find 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 8 December 2025.

Round-trip from

£118

One-way from

£59

Popular in

June

Cheapest in

January

Average price

£140
Southwest
  • Southwest
  • 7/1-10/1
  • Nonstop
  • 4h 45m total
  • Ontario to Denver
Search Deals
United Airlines
  • United Airlines
  • 10/1
  • Nonstop
  • 2h 19m total
  • Ontario to Denver
Search Deals
Highest demand for flights based on searches. 9% potential increase in price (£9 potential increase over avg. return price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease (£4 potential savings vs. average return price).
Search Deals
Average for round-trip flights in December 2025
Search Deals

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 8 December 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

Sat 14/2

05:00-08:16

Nonstop2h 16m

Denver Intl

Thu 19/2

19:20-20:50

Nonstop2h 30m

£131

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 13/1

16:03-23:35

1 stop6h 32m

Denver Intl

Wed 21/1

07:00-15:08

1 stop9h 08m

£132

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Wed 21/1

16:03-23:35

1 stop6h 32m

Denver Intl

Wed 28/1

07:00-15:08

1 stop9h 08m

£132

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Wed 14/1

16:03-23:35

1 stop6h 32m

Denver Intl

Thu 15/1

11:49-17:03

1 stop6h 14m

£145

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 13/1

15:30-23:25

1 stop6h 55m

Denver Intl

Tue 20/1

18:23-23:58

1 stop6h 35m

£148

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Mon 12/1

06:00-11:54

1 stop4h 54m

Denver Intl

Tue 20/1

07:00-12:16

1 stop6h 16m

£154

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 13/1

13:11-19:56

1 stop5h 45m

Denver Intl

Sun 18/1

15:59-21:48

1 stop6h 49m

£155

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sun 11/1

07:30-17:34

1 stop9h 04m

Denver Intl

Thu 15/1

06:29-13:56

1 stop8h 27m

£161

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sun 11/1

15:30-23:25

1 stop6h 55m

Denver Intl

Sun 18/1

15:59-21:48

1 stop6h 49m

£163

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Sat 14/2

07:05-15:15

2 stops7h 10m

Denver Intl

Thu 19/2

05:45-09:05

1 stop4h 20m

£163

Flights are sorted by cheapest return flights first.

Deals found on 7/12

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 5 December 2025.

Booking 88 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, March is the cheapest month in which you can book a flight from Ontario to Denver (average of £27). Flying from Ontario to Denver in September is currently the most expensive (average of £56). 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 8 December 2025.

It’s optimal to fly from Ontario to Denver in the evening. By choosing this option you can save up to 87% 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 6 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 5h 45m. 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 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: Frontier (87%), Southwest (80%), Air Canada( 78%).

  • 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, March is the cheapest month in which you can book a flight from Ontario to Denver (average of £27). Flying from Ontario to Denver in September is currently the most expensive (average of £56). 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

Browse thousands of different options on Cheapflights for your next trip

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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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