Cheap flights from Denver to Los Angeles from $27

In general, August is the cheapest month to fly from Denver to Ontario. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $142. If you aren’t able to travel during the month of August, then book flights to Ontario from Denver during May instead. Flights to Ontario in May, while not as cheap as those in August, still average around $145.

The cheapest day to depart on your flight to Ontario is on a Saturday when prices can be found for as low as $160. This is often the case because there is less demand to fly during this day of the week. When flying out on a Sunday, the most expensive travel day of the week, you can expect to see flight prices from Denver to Ontario for around $219.

In the evening is the cheapest time of day to fly from Denver to Ontario when you can find flight prices for as low as $174. Flying to Ontario in the evening is an ideal time because this is during off-peak travel hours. If you have a flexible travel schedule, then try to avoid flying at noon when prices are $197 on average. Flights to Ontario from Denver at noon are generally more expensive because this time of day is more convenient for travelers’ schedules.

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

You are more likely to see cheaper flights to Ontario from Denver when booking weeks ahead of your departure date. In general, you can expect to find flights to Ontario for around $188 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Ontario from Denver for as low as $131 on momondo.

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

Frontier is the most popular carrier operating from Denver Intl to Ontario

Frontier, United Airlines and Southwest are the top three most popular airlines that fly to Ontario from Denver according to our data. Frontier is the first choice among our users, with 53% of people opting to fly with this airline when traveling to Ontario. Keep in mind that there are 7 different airlines that fly to Ontario on a routine basis, so you have a few additional options to choose from.

As of February 2026, 6 flights take off from Denver and land in Ontario each day. The most common flight departure time for this route is 11:00AM, with 55% of daily flights taking off in the evening.

As of February 2026, 42 flights take off from Denver and land in Ontario each week. The most common flight departure day for this route is Tue, with 21% of weekly flights taking off on this day.