Skyscanner

Cheap Flights from Ontario International to Denver

Compare Ontario International to Denver flight deals

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

Book the best Denver fare with no extra fees

TrustScore 4.5 out of 5 4.5 out of 5 based on 795 reviews Trustpilot

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.C$59 per passenger.Departing Mon., Nov. 17.One-way flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Mon., Nov. 17, arriving in Denver International.Price includes taxes and charges.From C$59, select.
Denver.C$59 per passenger.Departing Thu., Dec. 11.One-way flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Thu., Dec. 11, arriving in Denver International.Price includes taxes and charges.From C$59, select.
Denver.C$59 per passenger.Departing Sat., Oct. 11.One-way flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Sat., Oct. 11, arriving in Denver International.Price includes taxes and charges.From C$59, select.
Denver.C$67 per passenger.Departing Fri., Sep. 26.One-way flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Fri., Sep. 26, arriving in Denver International.Price includes taxes and charges.From C$67, select.
Denver.C$92 per passenger.Departing Sat., Jan. 10.One-way flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Sat., Jan. 10, arriving in Denver International.Price includes taxes and charges.From C$92, select.
Denver.C$97 per passenger.Departing Sat., Feb. 14.One-way flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Sat., Feb. 14, arriving in Denver International.Price includes taxes and charges.From C$97, select.
Denver.C$216 per passenger.Departing Wed., Mar. 18.One-way flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Ontario International on Wed., Mar. 18, arriving in Denver International.Price includes taxes and charges.From C$216, select.
Denver.C$216 per passenger.Departing Sun., Apr. 12.One-way flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Ontario International on Sun., Apr. 12, arriving in Denver International.Price includes taxes and charges.From C$216, 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 October.
Sep.
from C$67
Oct.
from C$59
Nov.
from C$59
Dec.
from C$59
Jan.
from C$92
Feb.
from C$97
Mar.
from C$216
Apr.
from C$216
May
from C$288
Jun.
from C$289
Jul.
Find prices
Aug.
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.

Ontario to Denver: Flight information

The things to know before you go.
Cheapest flight foundC$59
Cheapest month to flyNovember
Average flight time2 hrs, 17 mins
Most popular airlineSouthwest Airlines
Average flights per week200

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 C$113. 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 17 minutes is the average flight time from Ontario International to Denver.
Southwest Airlines, United and Air Canada fly direct from Ontario International to Denver.
As of September 2025, there are 100 flights per week flying from Ontario International to Denver.
The cheapest month to fly from Ontario International to Denver is usually November.
If you're flying from Ontario International Airport, the cheapest airport near Denver is Denver International – which is 29.9 km away from the centre of Denver. We've found flights into this airport from C$113.
After crunching the numbers on our flight calendar, we found that it's currently cheapest to fly from Ontario International Airport to Denver on Sunday, November 16, 2025.
Yes – the average flight time is 2 hours and 17 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 September, the average temperature is usually around 17°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.

Flying 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 19 minutes.

  • The timezone in Denver is UTC-6. The city is 1 hour ahead of Ontario, where Ontario International Airport is located.

  • The busiest route is from Ontario International Airport (ONT) to Denver International Airport (DEN). You can select from 54 weekly services between these two airports. If you'd like to get going as soon as possible, the earliest flight from ONT to DEN is the 00:39 Frontier Airlines service. If you'd rather fly out later on, the last departure is at 22:23 with Frontier Airlines.

  • To ensure you catch your flight from ONT to Denver, leave enough time to navigate the airport and find your gate. Turning up two hours before international departures and an hour before domestic flights is the general rule.

  • Getting away during a peak time like August? Popular seasons (like Thanksgiving, Christmas/New Year and spring break) can add another hour at check-in and security. Be extra cautious and arrive up to four hours ahead of an international flight and two hours before a domestic departure.

  • You can catch a nonstop flight from Ontario International Airport to Denver that lands at Denver International Airport (DEN).

  • You'll have your choice of carriers operating direct flights from Ontario International Airport to Denver. Book your journey with one of these:

  • When flying domestically within United States, you won't need a passport or visa. However, you'll have to show another form of identification, such as an ID card or driver's licence. Once you've booked flight tickets from Ontario International Airport to Denver, make sure your ID is up to date.

  • ONT is about 6 kilometres from central Ontario. If you're catching a cab, ride-sharing or driving from the centre, it'll take you 10 minutes or so to get there, depending on the traffic. If you're using public transport, expect the travel time to be around 1 hour and 28 minutes.

  • Booked an early flight from Ontario International Airport to Denver? Avoid the stress of rushing to the airport (and sneak in some extra snooze time) by picking one of these hotels near ONT:

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

  • C$59 is the best price for a one-way ticket from Ontario International Airport to Denver. A return flight starts at C$113. These prices may change depending on demand and availability.

  • Book 9 months before travelling. After crunching the numbers on our calendar, this is how far you'll want to book ahead to find cheap tickets from ONT to Denver.

  • The cheapest month for tickets from Ontario International Airport to Denver is May. You can easily compare prices using the 'Whole month' tool and choose the date that offers the lowest fare.

  • Set up a Price Alert for cheap tickets from ONT to Denver. There's no need to look every day to see if prices have dropped. We'll let you know when the price changes.

  • Use the filters to tailor your flights from Ontario International Airport to Denver. Simply enter your preferred departure and arrival times, airlines and number of stops. Or sort your results by 'Cheapest' to find the best deals.

Airports in Denver

Denver International Airport (DEN)

  • Denver International Airport (DEN) to central Denver is approximately 40 kilometres. It'll take you around 34 minutes to get to the centre driving.

  • Getting there by public transport takes roughly 1 hour and 31 minutes.

  • Once your flight from Ontario International Airport to Denver has touched down, unwind at a hotel close by. SpringHill Suites Denver Airport is a great option that's an easy drive from DEN.

Best time to go to Denver

  • July is the busiest month to catch a flight from Ontario International Airport to Denver while April is the quietest. To work out the best time to go to Denver, consider the pace you prefer to travel at.

  • Before locking in your flight from Ontario International Airport to Denver, think about the type of weather you enjoy. July is the warmest month in Denver, with the temperature ranging from 14ºC to 32ºC.

  • January has average temperatures of between -9ºC and 7ºC. Search for cheap flights from ONT to Denver sometime then if you like cooler conditions.

More about Denver

  • Start your Denver trip off on the right foot by choosing the ideal place to stay. As soon as you've booked your flight from Ontario International Airport to Denver, browse our range of accommodation options including:

  • Denver Art Museum and Union Station are just two of the popular attractions to put on your Denver travel itinerary. Continue your sightseeing adventures at Denver Botanic Gardens.

Complete your Denver trip with a car rental

  • We use the same magic that helped you find your cheap flight from Ontario International Airport to Denver to track down incredible deals on car rentals. Search for your ride in seconds and easily compare your options. Plus you'll find everything you need to know about car rentals in Denver, from the most popular car type to the best time to book.

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.