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$36+ Cheap flights from Ontario (ONT) to the United States

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 10/21. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — LAX
Oct 11 — Oct 181
Sat 10/11
Sat 10/18
1 adult, Economy
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Cheap flight deals from Ontario to USA

Keep the following information in mind while searching for Ontario to USA flight deals. Data was last updated September 11, 2025.

Round-trip from

$66
(Kiwi.com)

One-way from

$36
(Cheapflightsfares)

Popular in

December

Cheapest in

January

Average price

$297

Good round-trip deal

$93 or less

Good one-way deal

$60 or less
From Ontario to USA
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One-way flight from Ontario to USA
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Highest demand for flights based on searches. 6% potential increase in price ($24 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease ($8 potential savings vs. average RT price).
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Average for round-trip flights in September 2025
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Price to beat on a round-trip flight from Ontario to USA.
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Price to beat on a one-way flight from Ontario to USA.
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Find flight deals from Ontario to USA

Cheapest flights from Ontario to USA
Explore the most affordable flight options available from Ontario to USA. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 11, 2025.

This Cheapflightsfares deal was found by Cheapflights users on 9/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/38:59 pmONT - DEN
Nonstop2h 27mFrontier
Sun 10/56:00 amDEN - ONT
Nonstop2h 23mFrontier
Deal found 9/10$67
This Booking.com deal was found by Cheapflights users on 9/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/16:53 amONT - DEN
Nonstop2h 25mFrontier
Sat 11/110:29 pmDEN - ONT
Nonstop2h 21mFrontier
Deal found 9/11$68
This Southwest deal was found by Cheapflights users on 9/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/99:35 pmONT - LAS
Nonstop1h 05mSouthwest
Thu 10/1610:00 pmLAS - ONT
Nonstop1h 00mSouthwest
Deal found 9/11$71
This Frontier deal was found by Cheapflights users on 9/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/118:00 amONT - LAS
Nonstop1h 12mFrontier
Tue 11/117:33 pmLAS - ONT
Nonstop1h 09mFrontier
Deal found 9/10$72
This Frontier deal was found by Cheapflights users on 9/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/86:53 amONT - DEN
Nonstop2h 25mFrontier
Wed 10/810:29 pmDEN - ONT
Nonstop2h 21mFrontier
Deal found 9/11$72
This Southwest deal was found by Cheapflights users on 9/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 10/59:05 pmONT - LAS
Nonstop1h 05mSouthwest
Wed 10/87:20 amLAS - ONT
Nonstop1h 05mSouthwest
Deal found 9/11$73
This Cheapflightsfares deal was found by Cheapflights users on 9/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/308:59 pmONT - DEN
Nonstop2h 27mFrontier
Sun 10/56:00 amDEN - ONT
Nonstop2h 23mFrontier
Deal found 9/11$73
This Priceline deal was found by Cheapflights users on 9/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/18:59 pmONT - DEN
Nonstop2h 27mFrontier
Sat 10/1110:29 pmDEN - ONT
Nonstop2h 21mFrontier
Deal found 9/11$74
This Frontier deal was found by Cheapflights users on 9/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/256:00 amONT - LAS
Nonstop1h 11mFrontier
Wed 10/157:33 pmLAS - ONT
Nonstop1h 09mFrontier
Deal found 9/11$76
This SmartFares deal was found by Cheapflights users on 9/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure SmartFares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/310:40 pmONT - SFO
Nonstop1h 35mFrontier
Mon 10/610:11 pmSFO - ONT
Nonstop1h 27mFrontier
Deal found 9/11$76
This Kiwi.com deal was found by Cheapflights users on 9/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/248:00 amONT - LAS
Nonstop1h 11mFrontier
Wed 9/248:49 pmLAS - ONT
Nonstop1h 07mFrontier
Deal found 9/11$77
This United Airlines deal was found by Cheapflights users on 9/9. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/16:00 amONT - SFO
Nonstop1h 24mUnited Airlines
Mon 11/39:30 pmSFO - ONT
Nonstop1h 21mUnited Airlines
Deal found 9/9$77

Cheapflights Fare Finder

 
Customize your flight search to find flights from Ontario to USA that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated September 11, 2025.
Use the filters below to find and compare flights from Ontario to the United States that are best for you.

Fly from

Ontario

Fly to

USA

Route

Depart

Return

Price

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Tue 10/14

7:04 am-10:31 am

Nonstop2h 27m

Denver Intl

Fri 10/17

8:15 am-9:35 am

Nonstop2h 20m

$67

OntarioDenver

ONT - DEN

ONTDEN

Ontario

Wed 10/8

6:53 am-10:18 am

Nonstop2h 25m

Denver Intl

Sat 10/11

10:29 pm-11:50 pm

Nonstop2h 21m

$67

OntarioLas Vegas

ONT - LAS

ONTLAS

Ontario

Mon 10/27

9:35 pm-10:40 pm

Nonstop1h 05m

Las Vegas Harry Reid Intl

Wed 10/29

7:20 am-8:25 am

Nonstop1h 05m

$71

OntarioLas Vegas

ONT - LAS

ONTLAS

Ontario

Wed 10/1

9:00 pm-10:10 pm

Nonstop1h 10m

Las Vegas Harry Reid Intl

Thu 10/2

10:00 pm-11:00 pm

Nonstop1h 00m

$71

OntarioLas Vegas

ONT - LAS

ONTLAS

Ontario

Sun 10/5

9:05 pm-10:10 pm

Nonstop1h 05m

Las Vegas Harry Reid Intl

Wed 10/8

7:20 am-8:25 am

Nonstop1h 05m

$73

OntarioLas Vegas

ONT - LAS

ONTLAS

Ontario

Sat 10/11

8:45 pm-9:50 pm

Nonstop1h 05m

Las Vegas Harry Reid Intl

Mon 10/13

10:00 pm-11:00 pm

Nonstop1h 00m

$73

OntarioLas Vegas

ONT - LAS

ONTLAS

Ontario

Sun 10/12

9:05 pm-10:10 pm

Nonstop1h 05m

Las Vegas Harry Reid Intl

Mon 10/13

10:00 pm-11:00 pm

Nonstop1h 00m

$75

OntarioLas Vegas

ONT - LAS

ONTLAS

Ontario

Wed 10/1

9:00 pm-10:10 pm

Nonstop1h 10m

Las Vegas Harry Reid Intl

Tue 10/7

7:20 am-8:25 am

Nonstop1h 05m

$82

OntarioLas Vegas

ONT - LAS

ONTLAS

Ontario

Fri 9/26

10:28 pm-11:44 pm

Nonstop1h 16m

Las Vegas Harry Reid Intl

Thu 10/16

10:37 am-11:47 am

Nonstop1h 10m

$84

OntarioSan Francisco

ONT - SFO

ONTSFO

Ontario

Thu 10/2

9:46 pm-11:15 pm

Nonstop1h 29m

San Francisco

Fri 10/10

10:43 pm-12:12 am

Nonstop1h 29m

$86

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/11

Showing 1-10 of 60 results
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Best time to book a flight from Ontario to USA

Have a flexible travel schedule? Discover the best time to fly to USA from Ontario with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from Ontario to the United States

What is the cheapest month to book a flight from Ontario to USA?

Currently, January is the cheapest month in which you can book a flight from Ontario to USA (average of $246). Flying from Ontario to USA in March is currently the most expensive (average of $325). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from ONT to US?

Find hourly flight availability from Ontario to USA. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated September 11, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Ontario to USA as you normally would.

Reviews of airlines servicing USA

Get insights into the airlines that provide service to USA. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to USA. Reviews last updated September 11, 2025.
Read reviews from past customers who have flown Southwest, Delta, and United Airlines from Ontario to the United States. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,248 reviews

Crew

8.6

Overall

8.0

Entertainment

7.5

Comfort

8.0

Food

7.0

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Southwest
8.0
Very good
4,248 reviews
Southwest
8.0
Very good
4,248 reviews

Crew

8.6

Overall

8.0

Entertainment

7.5

Comfort

8.0

Food

7.0

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Delta
8.0
Very good
7,960 reviews
Southwest
8.0
Very good
4,248 reviews

Crew

8.6

Overall

8.0

Entertainment

7.5

Comfort

8.0

Food

7.0

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
United Airlines
7.4
Good
8,937 reviews
Southwest
8.0
Very good
4,248 reviews

Crew

8.6

Overall

8.0

Entertainment

7.5

Comfort

8.0

Food

7.0

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
American Airlines
7.2
Good
10,000 reviews
Southwest
8.0
Very good
4,248 reviews

Crew

8.6

Overall

8.0

Entertainment

7.5

Comfort

8.0

Food

7.0

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Frontier
5.8
Fair
3,177 reviews
Southwest
8.0
Very good
4,248 reviews

Crew

8.6

Overall

8.0

Entertainment

7.5

Comfort

8.0

Food

7.0

Boarding

8.1

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.

Related info for your journey

Find useful and relevant information for your journey from Ontario to USA. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly from for flights from Ontario to United States?

    Ontario (ONT) is the airport you will fly out of if you book a flight from Ontario to United States. It is only a 3.1 mi journey to Ontario (ONT) from Ontario’s city center.

  • How long is the flight from Ontario to USA?

    Departing from Ontario to USA will take you 1h 05m. The distance from Ontario to USA is about 197 mi. Generally, flights for this route are nonstop.

  • What are the cheapest airlines to fly from Ontario to USA one-way?

    $36 is the cheapest one-way deal found within the past few days, from Southwest. You may also be able to find cheap deals on United Airlines and Frontier, with prices starting from $39 and $54, respectively.

  • What are the most popular routes from Ontario to USA?

    While some choose either Ontario - Seattle/Tacoma Intl or Ontario - Newark, Ontario - New York John F Kennedy Intl is the most popular route from Ontario to USA.

  • Can I find deals for flights from Ontario to USA that include hotel bookings?

    Yes. In addition to deals on Ontario to USA flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Ontario to USA?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Ontario to USA.

  • Can I find deals for business class flights from Ontario to USA?

    Yes. Cheapflights offers flight deals from Ontario to USA by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Ontario to USA?

    Currently, January is the cheapest month in which you can book a flight from Ontario to USA (average of $246). Flying from Ontario to USA in March is currently the most expensive (average of $325). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

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Alternative routes for Ontario to USA

See prices for flight routes from nearby airports that may be better suited for you.
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Top 8 airlines flying from Ontario to USA

Discover the top 8 airlines that operate flights from Ontario to USA. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated September 11, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$22Average$143FlexibilityNo cancel feeOn-time65%
FrontierCheapest$36Average$187FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$58Average$395FlexibilityNo cancel feeOn-time69%
Alaska AirlinesCheapest$67Average$362FlexibilityNo cancel feeOn-time75%
DeltaCheapest$97Average$361FlexibilityNo cancel feeOn-timeN/A
SouthwestCheapest$97Average$373FlexibilityNo cancel feeOn-time63%
JetBlueCheapest$207Average$339FlexibilityNo cancel feeOn-time62%
American AirlinesCheapest$237Average$427FlexibilityNo cancel feeOn-time71%

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