Cheap flights from Ontario to Denver

One-way fares from $24 · ONT → DEN · prices found by travellers in the last 48 hours

Compare all dates Denver → Ontario
Cheapest fare
$24

Frontier Airlines · Thu, Dec 10

Cheapest month
December

from $24

Direct flights
Yes

Southwest Airlines and Frontier Airlines

Flight time
2h 10m

1,290 km

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Cheapest month to fly from Ontario to Denver

Lowest one-way fare per person in each month. Choose a month to see every date.

  1. November 2026 $68
  2. December 2026 Cheapest $24

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About flights from Ontario to Denver

Ontario (ONT) and Denver (DEN) are about 1,290 km apart. Direct flights take around 2h 10m, and recent direct fares were with Southwest Airlines and Frontier Airlines. Over the next few months, one-way fares start from $24, and December 2026 is currently the cheapest month to fly.

These prices come from searches travellers made in the last 48 hours, so they move quickly. If you see a good fare, it's worth booking soon. FlightsExp is free to use: you book directly with our travel partner.

Frequently asked questions

How much is a flight from Ontario to Denver?

The cheapest one-way fare we've seen recently is $24 with Frontier Airlines, departing Thursday, December 10, 2026. Over the coming months, the lowest fare in each month ranges from $24 to $68.

What is the cheapest month to fly from Ontario to Denver?

December 2026 currently has the lowest fares, from $24 one way.

Are there direct flights from Ontario to Denver?

Yes. Recent direct fares were with Southwest Airlines and Frontier Airlines.

How long is the flight from Ontario to Denver?

A direct flight takes about 2h 10m. Ontario and Denver are around 1,290 km apart.

Which airlines fly from Ontario to Denver?

Recent fares on this route were with Southwest Airlines and Frontier Airlines.

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