Cheap Flights from Ontario, CA to Denver, CO from $37

On Cheapflightsplus.com you will find 10 direct and 209 connecting flights from Ontario to Denver. You can compare airfare deals from 4 airlines and multiple travel sites from $37, book and save on cheap plane tickets and last minute offers. Also check out ONT-DEN flight schedule to find best flight time, convenient departure and arrival airports.

Flight Information

Below we will explain in detail what the flights cost on the destination from Ontario to Denver depends on and how to choose the most interesting flight option for you.

Distance between Ontario and Denver is 1316 miles. Time difference between the cities is 1h. Airplanes depart 00:59 to 21:41 from 2 Ontario airports and arrive 00:59 to 21:41 to 2 Denver airports. Average flight time is 2h 17m.

  • The fastest flight 2h 16m
  • Average flight time 2h 17m
  • The earliest flight 00:59
  • The latest flight 21:41
  • Distance 818 ml

The cheapest months to travel to Denver are october (from 37 $), november (from 37 $), may (from 49 $).

The most expensive months are august (from 91 $), september (from 89 $), july (from 78 $).

What is the lowest airfare Ontario to Denver?

The cheapest plane ticket found by our users is $37. This airfare is for economy class on one-way F91500 flight by Frontier Airlines for October 21, 2025 which leaves Ontario Int. in Ontario at 00:59 am and arrives at Denver Denver International at 04:17.

Economy class
$37
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Business class
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First class
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Flight Schedule Ontario (California) to Denver (Colorado)

00:59 — 04:17
2h 18m flight time
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from$37
Ontario — Denver
F91500 Frontier Airlines
05:05 — 08:23
2h 18m flight time
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from$113
Ontario — Denver
UA1575 United Airlines
05:10 — 08:27
2h 17m flight time
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from$106
Ontario — Denver
UA2446 United Airlines
05:10 — 08:27
2h 17m flight time
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from$107
Ontario — Denver
UA1479 United Airlines
06:00 — 12:06
5h 6m flight time
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from$86
17:26 — 18:36 Ontario — Las Vegas
F92232 Frontier Airlines
1h 45m stop
08:18 — 11:19 Las Vegas — Denver
F92016 Frontier Airlines
12:40 — 23:02
9h 22m flight time
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from$86
12:40 — 18:11 Ontario — Houston
F93132 Frontier Airlines
2h 54m stop
21:05 — 23:02 Houston — Denver
F93227 Frontier Airlines
13:15 — 16:31
2h 16m flight time
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from$106
Ontario — Denver
UA1417 United Airlines
13:15 — 16:32
2h 17m flight time
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from$107
Ontario — Denver
UA1697 United Airlines
13:35 — 16:51
2h 16m flight time
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from$158
Ontario — Denver
UA1942 United Airlines
17:15 — 22:45
4h 30m flight time
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from$69
13:17 — 14:29 Ontario — Las Vegas
F91358 Frontier Airlines
1h 12m stop
20:33 — 23:36 Las Vegas — Denver
F94612 Frontier Airlines
17:21 — 20:42
2h 21m flight time
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from$49
Ontario — Denver
F92908 Frontier Airlines
17:26 — 04:00+1day
9h 34m flight time
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from$69
09:26 — 10:33 Ontario — Las Vegas
F91358 Frontier Airlines
6h 20m stop
06:30 — 09:38 Las Vegas — Denver
F91994 Frontier Airlines
17:26 — 12:19+1day
17h 53m flight time
Find flight
from$69
13:17 — 14:29 Ontario — Las Vegas
F91358 Frontier Airlines
14h 35m stop
08:18 — 11:19 Las Vegas — Denver
F92016 Frontier Airlines
18:28 — 21:47
2h 19m flight time
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from$137
Ontario — Denver
UA635 United Airlines
18:38 — 21:55
2h 17m flight time
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from$106
Ontario — Denver
UA368 United Airlines
Full flight schedule will help you in detecting at what time planes fly from Ontario to Denver. You can also specify the concrete flights and airlines on the route and how long the flight actually is. Use the calendar for today, tomorrow or other specific date as some flights are available only on certain days of the week.
*Departure and arrival times - local. Updated on October 15, 2025.

Popular Airlines on the Route

The flight Ontario — Denver is served by 4 regular airlines and 1 low-cost airline. Most of the flights on this route are operated by Alaska Airlines - 68 departures per week at the price of from $ 121 . And the most expensive tickets are offered by Hawaiian Airlines airline - from $ 673.

Direct flights

There are 10 nonstop flights on the route. The fastest direct flight is UA1417 by United Airlines takes 2h 16m and the cheapest is F91500 by Frontier Airlines for $37.

  • F9 - Frontier Airlines
    from $37
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  • UA - United Airlines
    from $106
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Connecting Flights

There are 209 flights with layovers on the route. The fastest connecting flight is F91358 by Frontier Airlines takes 4h 30m and the cheapest is F91500 by Frontier Airlines for $69.

  • AS - Alaska Airlines
    from $121
    Find
  • F9 - Frontier Airlines
    from $69
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  • HA - Hawaiian Airlines
    from $113
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  • UA - United Airlines
    from $176
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See more connecting flights

Airports

You can fly from Ontario to Denver from 2 airports (Ontario Int., International Heliport).

Ontario airports

  • Ontario Int.-ONT
    from $37
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  • International Heliport-JIO
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Denver airports

  • Denver International-DEN
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  • Arapahoe Co-APA
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How to book a plane ticket yourself?

How to book an air ticket yourself?
  • Fill in the search parameters — cities of departure and destination, departure and return dates and click «Find flights»
  • Select the best flight that you like. Please, check the airports of departure and arrival. Select the best fare, but pay attention to the following flight details - airports of departure and arrival, flight duration and layovers. Please use filters and sort to find the best flight.
  • Click «Buy» when you are ready — our system will redirect you to the site that sells the selected flight ticket.
  • Fill in all passenger and payment information — passport and contact information, please double check all passengers’ names and make a payment for your itinerary.
  • That's it — you will receive an email with your e-ticket usually within 10 minutes after your flight is confirmed. Please, print the e-ticket and have it with you at the airport. You would need to have only a passport and/or a required form of ID to travel. Please, check your Visa requirements if you travel outside of the United States or Canada.

    To find a plane ticket, please select dates.

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