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$39+ Cheap flights from San Francisco to Ontario (SFO - ONT)

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 11/8. Fares are subject to change and may not be available on all flights or dates of travel.
SFO — ONT
Oct 15 — Oct 221
Wed 10/15
Wed 10/22
1 adult, Economy
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Cheapflights Tip: The best prices from San Francisco to Ontario are usually found in February or October, booked 89 days in advance, depart on a Monday or Saturday and return on a Friday

Cheap flight deals from San Francisco to Ontario

Discover tips and strategies to find the most affordable flight options for your journey from San Francisco (SFO) to Ontario (ONT). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated September 15, 2025.

Round-trip from

$72
(Cheapflightsfares)

One-way from

$39
(United Airlines)

Popular in

December

Cheapest in

February

Average price

$137

Good round-trip deal

$94 or less

Good one-way deal

$67 or less
From San Francisco to Ontario
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One-way flight from San Francisco to Ontario
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Highest demand for flights based on searches. 11% potential increase in price ($20 potential increase over avg. RT price).
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Cheapest flight prices on average. 5% 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 San Francisco to Ontario.
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Price to beat on a one-way flight from San Francisco to Ontario.
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Find flight deals from San Francisco to Ontario

Cheapest flights from San Francisco to Ontario
Explore the most affordable flight options available from San Francisco to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 15, 2025.

This Cheapflightsfares deal was found by Cheapflights users on 9/12. 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.
Mon 9/2910:11 pmSFO - ONT
Nonstop1h 27mFrontier
Thu 10/29:46 pmONT - SFO
Nonstop1h 29mFrontier
Deal found 9/12$72
This Flightnetwork deal was found by Cheapflights users on 9/14. 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 Flightnetwork is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/1510:11 pmSFO - ONT
Nonstop1h 27mFrontier
Mon 9/229:46 pmONT - SFO
Nonstop1h 29mFrontier
Deal found 9/14$74
This United Airlines deal was found by Cheapflights users on 9/13. 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.
Mon 10/69:30 pmSFO - ONT
Nonstop1h 22mUnited Airlines
Sat 10/116:51 pmONT - SFO
Nonstop1h 19mUnited Airlines
Deal found 9/13$77
This Cheapflightsfares deal was found by Cheapflights users on 9/14. 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.
Sun 10/1210:38 pmSFO - ONT
Nonstop1h 29mFrontier
Sun 10/1910:40 pmONT - SFO
Nonstop1h 29mFrontier
Deal found 9/14$78
This Frontier deal was found by Cheapflights users on 9/13. 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.
Fri 10/1710:43 pmSFO - ONT
Nonstop1h 29mFrontier
Fri 10/2410:50 pmONT - SFO
Nonstop1h 29mFrontier
Deal found 9/13$79
This Cheapflightsfares deal was found by Cheapflights users on 9/14. 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.
Thu 9/2510:11 pmSFO - ONT
Nonstop1h 27mFrontier
Thu 10/29:46 pmONT - SFO
Nonstop1h 29mFrontier
Deal found 9/14$82
This Cheapflightsfares deal was found by Cheapflights users on 9/13. 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 11/1410:21 pmSFO - ONT
Nonstop1h 29mFrontier
Sun 11/1610:50 pmONT - SFO
Nonstop1h 29mFrontier
Deal found 9/13$83
This Cheapflightsfares deal was found by Cheapflights users on 9/14. 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 9/2610:11 pmSFO - ONT
Nonstop1h 27mFrontier
Mon 9/299:46 pmONT - SFO
Nonstop1h 29mFrontier
Deal found 9/14$86
This United Airlines deal was found by Cheapflights users on 9/14. 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.
Tue 11/184:13 pmSFO - ONT
Nonstop1h 21mUnited Airlines
Sat 11/226:00 amONT - SFO
Nonstop1h 24mUnited Airlines
Deal found 9/14$88
This Cheapflightsfares deal was found by Cheapflights users on 9/14. 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.
Thu 11/610:11 pmSFO - ONT
Nonstop1h 29mFrontier
Mon 11/1010:40 pmONT - SFO
Nonstop1h 29mFrontier
Deal found 9/14$91

Cheapflights Fare Finder

 
Customize your flight search to find flights from San Francisco to Ontario 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 15, 2025.
Use the filters below to find and compare flights from San Francisco to Ontario that are best for you.

Fly from

San Francisco

Fly to

Ontario

Route

Depart

Return

Price

San FranciscoOntario

SFO - ONT

SFOONT

San Francisco

Sat 10/25

9:30 pm-10:52 pm

Nonstop1h 22m

Ontario

Wed 10/29

6:38 pm-8:02 pm

Nonstop1h 24m

$77

San FranciscoOntario

SFO - ONT

SFOONT

San Francisco

Sat 11/15

5:00 am-11:30 am

1 stop6h 30m

Ontario

Mon 11/17

3:30 pm-9:50 pm

1 stop6h 20m

$135

San FranciscoOntario

SFO - ONT

SFOONT

San Francisco

Mon 10/13

10:45 am-12:13 pm

Nonstop1h 28m

Ontario

Tue 10/14

9:36 am-10:55 am

Nonstop1h 19m

$137

San FranciscoOntario

SFO - ONT

SFOONT

San Francisco

Wed 10/29

9:30 pm-10:51 pm

Nonstop1h 21m

Ontario

Thu 10/30

1:40 pm-3:04 pm

Nonstop1h 24m

$137

San FranciscoOntario

SFO - ONT

SFOONT

San Francisco

Mon 10/6

9:30 pm-10:52 pm

Nonstop1h 22m

Ontario

Wed 10/15

6:36 pm-7:55 pm

Nonstop1h 19m

$137

San FranciscoOntario

SFO - ONT

SFOONT

San Francisco

Sat 11/15

4:13 pm-5:34 pm

Nonstop1h 21m

Ontario

Sun 11/16

6:00 am-7:24 am

Nonstop1h 24m

$137

San FranciscoOntario

SFO - ONT

SFOONT

San Francisco

Wed 10/15

9:30 pm-10:52 pm

Nonstop1h 22m

Ontario

Thu 10/16

1:53 pm-3:11 pm

Nonstop1h 18m

$137

San FranciscoOntario

SFO - ONT

SFOONT

San Francisco

Sat 10/11

9:30 pm-10:52 pm

Nonstop1h 22m

Ontario

Fri 10/17

9:36 am-10:55 am

Nonstop1h 19m

$137

San FranciscoOntario

SFO - ONT

SFOONT

San Francisco

Tue 10/7

4:20 pm-5:40 pm

Nonstop1h 20m

Ontario

Thu 10/16

1:53 pm-3:11 pm

Nonstop1h 18m

$137

San FranciscoOntario

SFO - ONT

SFOONT

San Francisco

Tue 10/7

4:20 pm-5:40 pm

Nonstop1h 20m

Ontario

Sat 10/11

1:53 pm-3:11 pm

Nonstop1h 18m

$137

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/15

Showing 1-10 of 22 results
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The best insider tips for San Francisco to Ontario flights

Snippets provided in this section are AI-generated based on a summarization of Cheapflights-commissioned articles. The articles are presented as-is, for general informational purposes only, and may not be up-to-date. The opinions contained in the articles are original to the author and reflect their authentic experience, which may vary significantly from the experience of others.
Cheapflights partnered with top experts to bring you the best recommendations for your San Francisco to Ontario trip
Airports
SFO

Save time by using the SFO2Go program to order meals for pickup during busy times.

Read more about SFOby Harriet Baskas
ONT

Consider renting a car at ONT for convenient travel in the L.A. area.

Read more about ONTby Bill Fink
Our travel experts
Bill Fink

Bill Fink

Expert on ONT

Bill Fink

Bill Fink

Bill is an award-winning travel writer with extensive credits covering airlines and the aviation industry for publications including AARP, AFAR, The Points Guy and Yahoo. Based in Portland, Oregon, Bill has traveled to more than 75 countries - and been late for his flight in most of them. He once achieved top-level frequent flier status for all of American, Delta and United Airlines during a single year.

Read more
Harriet Baskas

Harriet Baskas

Expert on SFO

Harriet Baskas

Harriet Baskas

Harriet is an award-winning journalist who is happiest in an airport or an unusual museum. Her stories about airports, air travel, and the business of travel have appeared on NBC News, CNBC, USA TODAY, The Points Guy and other outlets. She is the creator of the StuckatTheAirport.com blog and the author of nine books. When not out on the road or exploring the latest airport amenities, she’s home in Seattle getting ready for the next adventure.

Read more

Best time to book a flight from San Francisco to Ontario

Have a flexible travel schedule? Discover the best time to fly to Ontario from San Francisco 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 San Francisco to Ontario

How far ahead should I book a flight from San Francisco to Ontario?

Use this chart to determine the optimal time to book a round-trip flight from San Francisco to Ontario. Price data was last updated on September 12, 2025.

Booking 89 days in advance of your planned departure date is, on average, the best time to get cheap flights from San Francisco to Ontario. The general trend is that the closer you book to the departure date, the more expensive your flight will be.

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

Currently, August is the cheapest month in which you can book a flight from San Francisco to Ontario (average of $246). Flying from San Francisco to Ontario in March is currently the most expensive (average of $328). 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 SFO to ONT?

Find hourly flight availability from San Francisco to Ontario. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated September 15, 2025.

Unlike in the afternoon, when flights are generally more expensive, you can save up to 34% on flights from San Francisco to Ontario by exploring options for tickets at noon.

What is the cheapest day to fly from San Francisco to Ontario?

Use this chart to determine the cheapest time to fly round-trip from San Francisco to Ontario. Price data was last updated on September 14, 2025.

Travelers seeking maximum savings on their San Francisco to Ontario flight should consider departing on Saturday evenings when fares are most often at their lowest. Friday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.

Reviews of airlines servicing Ontario

Get insights into the airlines that provide service to Ontario. 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 Ontario. Reviews last updated September 15, 2025.
Peruse reviews from past customers who have flown with Alaska Airlines, Delta, and United Airlines from San Francisco to Ontario to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Boarding

8.1

Entertainment

7.0

Food

7.1

Comfort

7.8

Overall

8.0

Reviews

1 / 20
6.0
Good

Hannah,Aug 2025

SFO - SAN

Ticket said TSA pre check, but then the TSA agent said that Alaska Airlines has not actually entered the pre check information for the ticket, so I had to use regular security. During boarding, I have a disability and need to board early. The Alaska Airlines employee announced disability boarding, but then immediately announced 2 other groups to board, so I still had to fight the crowds. On the plane, the stewardess was brusk and rude. Seats were very uncomfortable, especially on lower back.
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Boarding

8.1

Entertainment

7.0

Food

7.1

Comfort

7.8

Overall

8.0

Reviews

1 / 20
6.0
Good

Hannah,Aug 2025

SFO - SAN

Ticket said TSA pre check, but then the TSA agent said that Alaska Airlines has not actually entered the pre check information for the ticket, so I had to use regular security. During boarding, I have a disability and need to board early. The Alaska Airlines employee announced disability boarding, but then immediately announced 2 other groups to board, so I still had to fight the crowds. On the plane, the stewardess was brusk and rude. Seats were very uncomfortable, especially on lower back.
Delta
8.0
Very good
7,954 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Boarding

8.1

Entertainment

7.0

Food

7.1

Comfort

7.8

Overall

8.0

Reviews

1 / 20
6.0
Good

Hannah,Aug 2025

SFO - SAN

Ticket said TSA pre check, but then the TSA agent said that Alaska Airlines has not actually entered the pre check information for the ticket, so I had to use regular security. During boarding, I have a disability and need to board early. The Alaska Airlines employee announced disability boarding, but then immediately announced 2 other groups to board, so I still had to fight the crowds. On the plane, the stewardess was brusk and rude. Seats were very uncomfortable, especially on lower back.
United Airlines
7.4
Good
8,929 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Boarding

8.1

Entertainment

7.0

Food

7.1

Comfort

7.8

Overall

8.0

Reviews

1 / 20
6.0
Good

Hannah,Aug 2025

SFO - SAN

Ticket said TSA pre check, but then the TSA agent said that Alaska Airlines has not actually entered the pre check information for the ticket, so I had to use regular security. During boarding, I have a disability and need to board early. The Alaska Airlines employee announced disability boarding, but then immediately announced 2 other groups to board, so I still had to fight the crowds. On the plane, the stewardess was brusk and rude. Seats were very uncomfortable, especially on lower back.
Spirit Airlines
6.3
Okay
8,015 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Boarding

8.1

Entertainment

7.0

Food

7.1

Comfort

7.8

Overall

8.0

Reviews

1 / 20
6.0
Good

Hannah,Aug 2025

SFO - SAN

Ticket said TSA pre check, but then the TSA agent said that Alaska Airlines has not actually entered the pre check information for the ticket, so I had to use regular security. During boarding, I have a disability and need to board early. The Alaska Airlines employee announced disability boarding, but then immediately announced 2 other groups to board, so I still had to fight the crowds. On the plane, the stewardess was brusk and rude. Seats were very uncomfortable, especially on lower back.
Frontier
5.8
Fair
3,172 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Boarding

8.1

Entertainment

7.0

Food

7.1

Comfort

7.8

Overall

8.0

Reviews

1 / 20
6.0
Good

Hannah,Aug 2025

SFO - SAN

Ticket said TSA pre check, but then the TSA agent said that Alaska Airlines has not actually entered the pre check information for the ticket, so I had to use regular security. During boarding, I have a disability and need to board early. The Alaska Airlines employee announced disability boarding, but then immediately announced 2 other groups to board, so I still had to fight the crowds. On the plane, the stewardess was brusk and rude. Seats were very uncomfortable, especially on lower back.

Related info for your journey

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

  • What airports do I use to fly from San Francisco to Ontario?

    Ontario is the airport most travelers will use when flying to Ontario from San Francisco. Booking flights from San Francisco (SFO) to Ontario (ONT) should be relatively easy as there are 6 daily flights to Ontario from 6 different airlines. 1h 20m is how long a flight from San Francisco to Ontario will take if you book a nonstop flight.

  • How popular is this San Francisco to Ontario flight route?

    Within the past month, 72 users have taken a look at flights from San Francisco to Ontario.

  • How long is the flight from San Francisco to Ontario?

    A quick flight from San Francisco to Ontario can take about 1h 22m. United Airlines provides one of the quickest options available for as low as $77. San Francisco and Ontario are separated by a distance of 363 mi. This flight may include one or multiple stops.

  • What are the cheapest airlines flying from San Francisco to Ontario round-trip?

    Flying on Frontier is currently your cheapest option to Ontario, with prices starting at $38. Additional round-trip tickets that might be worth considering are offered by Spirit Airlines and United Airlines, with the lowest prices starting at $42 and $58, respectively. You may be able to fly from San Francisco to Ontario for 74% less than the average price by searching for these airlines.

  • What are the most reliable airlines from San Francisco to Ontario?

    No one likes to see their flight delayed. When booking a flight from San Francisco to Ontario consider choosing SkyWest Airlines (83%), United Airlines (82%) or Air Canada (79%) as they are the most reliable in getting you off to your destination on time.

  • What are the cheapest flights from San Francisco to Ontario?

    On average you can expect to pay $123 for a flight from San Francisco to Ontario. The cheapest flight overall is $38 while the most popular route, (San Francisco - Ontario) is currently priced at $53.

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

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

  • How can I find direct flights from San Francisco to Ontario?

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

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

    Yes. Cheapflights offers flight deals from San Francisco to Ontario 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 San Francisco to Ontario?

    Currently, August is the cheapest month in which you can book a flight from San Francisco to Ontario (average of $246). Flying from San Francisco to Ontario in March is currently the most expensive (average of $328). 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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Top 6 airlines flying from San Francisco to Ontario

Discover the top 6 airlines that operate flights from San Francisco to Ontario. 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 15, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$38Average$109FlexibilityNo cancel feeOn-time62%
Spirit AirlinesCheapest$42Average$105FlexibilityNo cancel feeOn-time65%
United AirlinesCheapest$58Average$226FlexibilityNo cancel feeOn-time69%
Alaska AirlinesCheapest$59Average$197FlexibilityNo cancel feeOn-time75%
DeltaCheapest$75Average$188FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$186Average$221FlexibilityNo cancel feeOn-time71%

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