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Cheap Flights from Ontario International (ONT) to Denver (DENA)

Compare Ontario International to Denver flight deals

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Flight deals from Ontario International to Denver

Looking for a cheap last-minute deal or the best return flight from Ontario International to Denver? Find the lowest prices on one-way and return tickets right here.
Denver.£48 per passenger.Departing Wed, 8 Apr, returning Wed, 15 Apr.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Wed, 8 Apr, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Wed, 15 Apr, arriving in Ontario International.Price includes taxes and charges.From £48, select.
Denver.£49 per passenger.Departing Tue, 5 May, returning Tue, 5 May.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Tue, 5 May, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Tue, 5 May, arriving in Ontario International.Price includes taxes and charges.From £49, select.
Denver.£57 per passenger.Departing Wed, 18 Mar, returning Wed, 25 Mar.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Wed, 18 Mar, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Wed, 25 Mar, arriving in Ontario International.Price includes taxes and charges.From £57, select.
Denver.£75 per passenger.Departing Thu, 30 Apr, returning Sun, 3 May.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Thu, 30 Apr, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Sun, 3 May, arriving in Ontario International.Price includes taxes and charges.From £75, select.
Denver.£108 per passenger.Departing Wed, 25 Mar, returning Sat, 4 Apr.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Wed, 25 Mar, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Sat, 4 Apr, arriving in Ontario International.Price includes taxes and charges.From £108, select.
Denver.£148 per passenger.Departing Fri, 27 Feb, returning Sun, 1 Mar.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Ontario International on Fri, 27 Feb, arriving in Denver International.Inbound indirect flight with Frontier Airlines, departs from Denver International on Sun, 1 Mar, arriving in Ontario International.Price includes taxes and charges.From £148, select.
Denver.£173 per passenger.Departing Fri, 29 May, returning Mon, 1 Jun.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Fri, 29 May, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Mon, 1 Jun, arriving in Ontario International.Price includes taxes and charges.From £173, select.
Denver.£173 per passenger.Departing Tue, 11 Aug, returning Fri, 14 Aug.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Tue, 11 Aug, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Fri, 14 Aug, arriving in Ontario International.Price includes taxes and charges.From £173, select.

Find the cheapest month to fly from Ontario International to Denver

We’re always keeping an eye on fares, so you can find the best one in seconds. It looks like Ontario International to Denver flights are currently cheapest in April.
Feb
from £225
Mar
from £57
Apr
from £48
May
from £49
Jun
from £203
Jul
from £183
Aug
from £173
Sep
from £214
Oct
from £309
Nov
Find prices
Dec
from £323
Jan
Find prices

Direct flights from Ontario International to Denver

Alternative Ontario International to Denver routes

Looking for the cheapest, fastest or easiest route from Ontario International to Denver? You could fly into the following airports instead.

Denver Arapahoe Co

0 miles from central Denver
Closest
Search flights

Broomfield

14 miles from central Denver
Search flights

Denver International

19 miles from central Denver
Cheapest
from £48
Search flights

Northern Colorado Regional

49 miles from central Denver
Search flights

Ontario to Denver: Flight information

The things to know before you go.
Cheapest flight found£48
Cheapest month to flyApril
Average flight time2 hrs, 16 mins
Most popular airlineSouthwest Airlines
Average flights per week85

Finding cheap flights from Ontario International to Denver: Frequently asked questions

There are 4 airports in Denver: Denver Arapahoe Co, Broomfield, Denver International, and Northern Colorado Regional.
The best price we found for a return flight from Ontario International to Denver is £48. This is an estimate based on information collected from different airlines and travel providers over the last 4 days and is subject to change and availability.
2 hours and 16 minutes is the average flight time from Ontario International to Denver.
Southwest Airlines, Air Canada and United fly direct from Ontario International to Denver.
As of February 2026, there are 85 flights per week flying from Ontario International to Denver.
The cheapest month to fly from Ontario International to Denver is usually April.
If you're flying from Ontario International Airport, the cheapest airport near Denver is Denver International – which is 18.6 miles away from the centre of Denver. We've found flights into this airport from £48.
After crunching the numbers on our flight calendar, we found that it's currently cheapest to fly from Ontario International Airport to Denver on Wednesday, 8 April 2026.
Yes – the average flight time is 2 hours and 16 minutes.
We show every price from over 1,200 airlines and travel agents, comparing them all so you don’t have to. If you know you want to fly to Denver but you’re not ready to book, set up a Price Alert. We’ll track prices for you, and let you know when they rise or fall.
We crunched all the numbers in our flight calendar and it looks like the cheapest time to book a flight to Denver is around 40 days in advance, so don’t leave your flight to the last minute.
In February, the average temperature is usually around 0°C. July is typically the warmest month in Denver, when it usually averages around 31°C. You can expect the least rain in January. The coldest month is December, with temperatures averaging -6°C. The rainiest month is July.
Currently, Frontier Airlines offers the cheapest flight tickets to Denver.

Travelling from Ontario International Airport (ONT) to Denver: what you need to know

  • The average length of a direct flight from Ontario International Airport to Denver is 2 hours 20 minutes.

  • Denver is one hour ahead of Ontario, where Ontario International Airport is located. Denver follows the UTC-6 timezone.

  • With 38 flights a week between the two airports, Ontario International Airport (ONT) to Denver International Airport (DEN) is the most popular route. Frontier Airlines operates the earliest flight at 00:49. If you're eager to get more out of your day before taking off, the last flight from ONT to DEN is with Southwest Airlines at 21:30.

  • For a stress-free journey, arrive at the airport two hours ahead of international flights and an hour before domestic departures. This will give you enough time to board your ONT to Denver flight.

  • Travelling during a peak time like school or public holidays? Expect longer queues at check-in and security. Give yourself extra leeway and arrive up to four hours before international flights and two hours ahead of domestic departures.

  • You can book a direct Ontario International Airport to Denver ticket. Start your trip at ONT and end it at Denver International Airport (DEN).

  • Popular airlines that offer direct flights from Ontario International Airport to Denver include:

  • The journey from central Ontario to ONT takes about 1 hour 30 minutes by public transport. If you drive, ride-share or take a cab, you'll cover the 3 miles in 10 minutes or so, depending on traffic.

  • Want an easy start to your journey? Stay near ONT. Whether you've booked an early flight from Ontario International Airport to Denver or just don't like being rushed, these hotels are worth a look:

  • 83.6% of flights departing from Ontario International Airport touch down at their destination on schedule. With its impressive on-time stats, you're unlikely to experience delays when taking off from ONT.

  • ONT's address is 2900 E. Airport Drive.

How to find the cheapest flights from Ontario International Airport (ONT) to Denver

  • £24 is the lowest price we've seen for a one-way Ontario International Airport to Denver flight. A return plane ticket right now is £48. Depending on when and how early you book, these fares can change.

  • Book one month before flying. Research on pricing trends suggests this is the ideal window for finding cheap flights from ONT to Denver.

  • May is the best month for landing an amazing deal on Ontario International Airport to Denver tickets. If you want to travel at a different time of year, the 'Whole month' tool will show you the lowest prices across every month.

  • Never miss a deal on cheap flights from ONT to Denver by creating a Price Alert. You'll receive an email or push notification on the app when a new discounted fare appears.

  • Select your preferred departure and arrival times, number of stops and airlines with our filters. Then, sort the results for your flight from Ontario International Airport to Denver by 'Best,' 'Fastest' or 'Cheapest.'

Airports in Denver

Denver International Airport (DEN)

  • Denver International Airport (DEN) is around 25 miles from the centre of Denver. If you're getting a cab or a ride-share, the drive takes roughly 35 minutes.

  • It takes around 1 hour 30 minutes if you're travelling by public transport.

  • Consider staying at Baymont by Wyndham Denver International Airport after touching down from your flight from Ontario International Airport to Denver. It's a quick drive from DEN and a good option if you'd like to rest right after your journey.

  • Pick up a Denver International Airport rental car and discover Denver and beyond with your own wheels. Routes Car Rentals, Dollar and Budget are top providers you can book with here.

  • Lock in the best deal by booking your ride from Denver International Airport about one week before your flight from ONT to Denver.

  • The street address for DEN is 8500 Pena Boulevard.

Best time to go to Denver

  • Carefully consider your trip dates before securing your flight from Ontario International Airport to Denver. The city comes alive in high season, but hotel rates are often higher and major attractions can get busy. Plan your trip to Denver in low season for a quieter vibe.

  • Lock in an Ontario International Airport to Denver plane ticket with a departure in July if you want to explore the city during its warmest month. You can expect temperatures to range from 14ºC (57ºF) to 32ºC (90ºF).

  • January sees average temperatures of between -9ºC (16ºF) and 7ºC (45ºF). Look for a cheap ticket from ONT to Denver around that time if you like travelling in cooler conditions.

More about Denver

Explore more of United States

  • You've visited Denver, now it's time to discover other corners of United States. Journey about 65 miles south to Colorado Springs to check off its popular sights. From US Northern Command (USNORTHCOM) / North American Aerospace Defence Command (NORAD) Headquarters to Cheyenne Mountain Air Force Station and National Strength and Conditioning Association (NSCA), you'll have a packed itinerary ahead.

  • Pueblo is another favourite destination in United States and is around 100 miles south of Denver. No trip is complete without a visit to Pueblo Weisbrod Aircraft Museum, Rosemount Museum and Pueblo Zoo.

Plan the rest of your trip from Ontario to Denver

Prices shown on this page are estimated lowest prices only. Found in the last 45 days.