Cheap flights from Ontario to Denver from $33

The cheapest month to fly to Denver from Ontario is in February. Flight prices, which tend to average around $164, are often lower during this time because this is during the off-season. If you don’t want to visit Denver in February, then you should wait until January to fly from Ontario, when ticket prices are also cheap, with an average price of $168.

The cheapest day to depart on your flight to Denver is on a Saturday when prices can be found for as low as $294. This is often the case because there is less demand to fly during this day of the week. The most expensive day to fly to Denver is Sunday, with ticket prices averaging around $387.

The cheapest time of day to fly to Denver is in the evening when flights can be purchased for as low as $279. Flights in the morning are often more expensive with an average ticket price of $328.

Fly from Ontario to Denver Intl for the best Ontario - Denver Intl flight prices

You are more likely to see cheaper flights to Denver from Ontario when booking weeks ahead of your departure date. In general, you can expect to find flights to Denver for around $235 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Denver from Ontario for as low as $186 on momondo.

There are 4 cabin classes available to choose from on Ontario to Denver flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Southwest and Delta are the most popular carriers operating from Ontario to Denver Intl

Frontier, United Airlines and Southwest are the top three most popular airlines that fly to Denver from Ontario according to our data. Frontier is the first choice among our users, with 46% of people opting to fly with this airline when traveling to Denver. Keep in mind that there are 8 different airlines that fly to Denver on a routine basis, so you have a few additional options to choose from.

The number of flights available between Ontario and Denver is 4 per day as of September 2026. The most frequent departure time is 1:00PM, with 49% of daily flights leaving at noon.

As of September 2026, 33 flights take off from Ontario and land in Denver each week. The most common flight departure day for this route is Mon, with 42% of weekly flights taking off on this day.