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Cheap flights from Ontario International to Denver International

Compare Ontario International to Denver International flight deals

Find the cheapest month or even day of the year to fly to Denver International

Book the best Denver International fare with no extra fees

Flight deals from Ontario International to Denver International

Looking for a cheap last-minute deal or the best return flight from Ontario International to Denver International? Find the lowest prices on one-way and return tickets right here.
Denver.P6,498 per passenger.Departing Sat, 2 Aug, returning Sat, 9 Aug.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Sat, 2 Aug, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Sat, 9 Aug, arriving in Ontario International.Price includes taxes and charges.From P6,498, select.
Denver.P6,733 per passenger.Departing Mon, 22 Sep, returning Thu, 25 Sep.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Mon, 22 Sep, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Thu, 25 Sep, arriving in Ontario International.Price includes taxes and charges.From P6,733, select.
Denver.P6,733 per passenger.Departing Tue, 22 Jul, returning Wed, 23 Jul.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Tue, 22 Jul, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Wed, 23 Jul, arriving in Ontario International.Price includes taxes and charges.From P6,733, select.
Denver.P7,292 per passenger.Departing Thu, 31 Jul, returning Tue, 12 Aug.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Thu, 31 Jul, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Tue, 12 Aug, arriving in Ontario International.Price includes taxes and charges.From P7,292, select.
Denver.P8,470 per passenger.Departing Sat, 25 Oct, returning Tue, 28 Oct.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Sat, 25 Oct, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Tue, 28 Oct, arriving in Ontario International.Price includes taxes and charges.From P8,470, select.
Denver.P8,944 per passenger.Departing Wed, 27 Aug, returning Wed, 3 Sep.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Ontario International on Wed, 27 Aug, arriving in Denver International.Inbound direct flight with Southwest Airlines departs from Denver International on Wed, 3 Sep, arriving in Ontario International.Price includes taxes and charges.From P8,944, select.
Denver.P8,959 per passenger.Departing Tue, 4 Nov, returning Tue, 11 Nov.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Ontario International on Tue, 4 Nov, arriving in Denver International.Inbound direct flight with Southwest Airlines departs from Denver International on Tue, 11 Nov, arriving in Ontario International.Price includes taxes and charges.From P8,959, select.
Denver.P9,645 per passenger.Departing Sat, 28 Jun, returning Tue, 1 Jul.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Sat, 28 Jun, arriving in Denver International.Inbound direct flight with Frontier Airlines departs from Denver International on Tue, 1 Jul, arriving in Ontario International.Price includes taxes and charges.From P9,645, select.

Find the cheapest month to fly from Ontario International to Denver International

We’re always keeping an eye on fares, so you can find the best one in seconds. It looks like Ontario International to Denver International flights are currently cheapest in August.
Jun
from P9,930
Jul
from P6,733
Aug
from P6,498
Sep
from P6,733
Oct
from P8,470
Nov
from P8,959
Dec
from P13,161
Jan
from P22,491
Feb
from P32,872
Mar
Find prices
Apr
Find prices
May
Find prices

Direct flights from Ontario International to Denver International

Ontario International to Denver International: Alternative routes

Compare routes from Ontario International to Denver below. You may find an airport to fly into that's cheaper, faster, or easier than Denver International.

Ontario to Denver: Flight information

The things to know before you go.
Cheapest flight foundP6,498
Cheapest month to flyAugust
Average flight time2 hrs, 15 mins
Most popular airlineSouthwest Airlines
Average flights per week73

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

The best price we found for a return flight from Ontario International to Denver International is P6,498. 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 15 minutes is the average flight time from Ontario International to Denver International.
Southwest Airlines, United and Air Canada fly direct from Ontario International to Denver International.
As of June 2025, there are 73 flights per week flying from Ontario International to Denver International.
The cheapest month to fly from Ontario International to Denver International is usually June 2025.
After crunching the numbers on our flight calendar, we found that it's currently cheapest to fly from Ontario International Airport to Denver International Airport on Saturday, 2 August 2025.
Yes – the average flight time is 2 hours and 15 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 International 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.
Currently, Frontier Airlines offers the cheapest flight tickets to Denver International.

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

  • Jump on a direct flight from Ontario International Airport to Denver International Airport and you'll be travelling for an average of 2 hours 20 minutes.

  • Denver is one hour ahead of Ontario and is in the UTC-6 timezone.

  • Take your pick of 54 weekly Ontario International Airport to Denver International Airport flights. The 00:39 departure with Frontier Airlines is the earliest available. Frontier Airlines operates the last service of the day at 22:23.

  • For a smooth journey, turn up at the airport two hours ahead of international flights and an hour before domestic departures. This will give you plenty of time to board your ONT to DEN flight.

  • During popular months such as August, it's best to get to the airport well in advance. Arrive two hours before a domestic departure and four hours ahead for international flights when you fly during a high season in general.

  • A range of airlines operate direct flights from Ontario International Airport to Denver International Airport, so jetting to Denver (and then discovering more of United States!) is easy. Top carriers that fly nonstop include:

  • The airline with the highest passenger demand on this route is Frontier Airlines.

  • United Airlines tops the rankings as the most punctual carrier for ONT to DEN flights, with 89.84% of services landing as scheduled.

  • If you'd like to split up your journey, simply uncheck 'Direct flights only' when searching for your ticket from Ontario International Airport to Denver International Airport. These are the top stopovers between ONT and DEN:

    • Phoenix Sky Harbour International Airport

    • Harry Reid Airport (formerly McCarran Airport)

    • Salt Lake City International Airport

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

  • The lowest price we've seen for a one-way Ontario International Airport to Denver International Airport flight is P3,361. A return fare is currently P6,498. Depending on the availability and when you book, these fares can change.

  • To pick up cheap tickets from ONT to DEN, book your journey six months before your departure.

  • Organise your trip for May. That's the cheapest month for flights from Ontario International Airport to Denver International Airport. If you're flexible with your dates, try out the 'Whole month' tool to see the lowest airfare across each month.

  • Finding cheap flights from ONT to DEN couldn't be easier with Price Alerts. Simply create one of these automatic alerts and we'll get in touch when a lower fare pops up.

  • Secure the ideal flight for you with the help of the filters. To see the 'Best,' 'Cheapest' or 'Fastest' flights from Ontario International Airport to Denver International Airport, use the 'Sort by' tool. You can also filter results by departure and arrival times, airline, and number of stops.

Handy information about Ontario International Airport (ONT)

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

  • 83.6% of flights departing from Ontario International Airport reach their destination on schedule. With its dependable on-time performance, you're unlikely to face delays when setting off from ONT.

  • To reach Ontario International Airport from central Ontario, it takes about 10 minutes if you're travelling by car. This depends on traffic though. It's approximately 6 kilometres from the airport to the city centre.

  • Expect a journey time of around 1 hour 30 minutes on public transport.

  • Get your holiday off to a relaxed start by staying near ONT. Whether you've booked an early flight from Ontario International Airport to Denver International Airport or just don't want to be rushed, these stays are the answer:

Arriving at Denver International Airport (DEN)

  • Get off your Ontario International Airport to Denver International Airport flight and be in your hotel bed shortly after. If you're looking for a comfy option that's not too far from DEN, unpack your bags at Baymont by Wyndham Denver International Airport.

  • Get on the fast track to adventure by picking up a Denver International Airport rental car. Grab a set of wheels from Routes Car Rentals, Dollar or Budget and explore beyond Denver's usual tourist stops.

  • Reserving your vehicle from Denver International Airport around one week in advance boosts your odds of scoring a great price.

Getting from Denver International Airport (DEN) to central Denver

  • You'll find DEN at 8500 Pena Boulevard.

  • From Denver International Airport, Denver is approximately 40 kilometres away. It takes around 35 minutes to reach the centre driving.

  • When travelling on public transport, expect a journey time of roughly 1 hour 30 minutes.

When to fly to Denver International Airport (DEN)

  • The quietest month for a flight from Ontario International Airport to Denver International Airport is April, while July is the most popular. Pick the best time to go to Denver based on whether you prefer a bustling atmosphere or a more laid-back vibe.

  • Before locking in your flight from Ontario International Airport to Denver International Airport, consider the kind of weather you like. July is the warmest month in Denver, with temperatures ranging from 14ºC (57ºF) to 32ºC (90ºF).

  • For cooler conditions, look for a cheap ticket from ONT to DEN in January. Average temperatures are between -9ºC (16ºF) and 7ºC (45ºF) then.

Explore more of United States

  • Denver has plenty to offer, but there are so many other parts of United States waiting to be explored. Around 105 kilometres south of Denver, a trip to Colorado Springs will keep your itinerary busy. Check out popular attractions like US Northern Command (USNORTHCOM) / North American Aerospace Defence Command (NORAD) Headquarters, Cheyenne Mountain Air Force Station and National Strength and Conditioning Association (NSCA).

  • Around 13 kilometres east of Denver, Aurora is another favourite stop in United States. Experience the best of this destination with a visit to Magellan's Travel Solutions and Gear, The Fairways at Lowry and Retired Enlisted Association Inc.

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.