Cheap flights from Chicago to Los Angeles from $77

In general, October is the cheapest month to fly from Chicago to Ontario. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $236. If you aren’t able to travel during the month of October, then book flights to Ontario from Chicago during August instead. Flights to Ontario in August, while not as cheap as those in October, still average around $323.

The cheapest day to depart on your flight to Ontario is on a Wednesday when prices can be found for as low as $434. This is often the case because there is less demand to fly during this day of the week. When flying out on a Monday, the most expensive travel day of the week, you can expect to see flight prices from Chicago to Ontario for around $541.

At noon is the cheapest time of day to fly from Chicago to Ontario when you can find flight prices for as low as $417. Flying to Ontario at noon is an ideal time because this is during off-peak travel hours. If you have a flexible travel schedule, then try to avoid flying in the morning when prices are $543 on average. Flights to Ontario from Chicago in the morning are generally more expensive because this time of day is more convenient for travelers’ schedules.

Fly from Chicago O'Hare Intl to Ontario for the best Chicago - Ontario flight prices

You are more likely to see cheaper flights to Ontario from Chicago when booking weeks ahead of your departure date. In general, you can expect to find flights to Ontario for around $399 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Ontario from Chicago for as low as $227 on momondo.

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

You could potentially save up to 37% on your flight if you consider stops on a Chicago to Ontario flight.

As of March 2026, prices for Chicago to Ontario flights are approximately 19% more expensive when compared to flights at the same time last year.

Frontier, United Airlines, and Delta are the most popular carriers operating from Chicago to Ontario

American Airlines, United Airlines and Frontier are the top three most popular airlines that fly to Ontario from Chicago according to our data. American Airlines is the first choice among our users, with 40% of people opting to fly with this airline when traveling to Ontario. Keep in mind that there are 8 different airlines that fly to Ontario on a routine basis, so you have a few additional options to choose from.

Las Vegas (LAS) was the most common stop: 44% of momondo users choosing 1-stop flights on this route connected there.

Flights via Las Vegas (LAS) offer the lowest average round-trip price of $152.

Flights connecting via Phoenix (PHX) have the shortest average one-way travel time: 5h 51m.

Phoenix (PHX) has the shortest average layover time for this route: 0h 53m.

As of March 2026, there are 1 flights per day flying from Chicago to Ontario. The most common time of day flights depart is 7:00PM, with 66% of flights taking off in the evening.

As of March 2026, 7 flights take off from Chicago and land in Ontario each week. The most common flight departure day for this route is Sun, with 43% of weekly flights taking off on this day.