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$29+ Cheap flights from Ontario to San Francisco (ONT - SFO)

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 8/12. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — SFO
Jul 5 — Jul 121
Sat 7/5
Sat 7/12
1 adult, Economy
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Cheapflights Tip: The best prices from Ontario to San Francisco are usually found in May or August, booked 89 days in advance, depart on a Friday or Thursday and return on a Monday

Cheap flight deals from Ontario to San Francisco

Discover tips and strategies to find the most affordable flight options for your journey from Ontario (ONT) to San Francisco (SFO). 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 June 30, 2025.

Round-trip from

$57
(Kiwi.com)

One-way from

$29
(United Airlines)

Popular in

November

Cheapest in

May

Average price

$129

Good round-trip deal

$109 or less

Good one-way deal

$69 or less
From Ontario to San Francisco
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One-way flight from Ontario to San Francisco
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Highest demand for flights based on searches. 13% potential increase in price ($17 potential increase over avg. RT price).
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Cheapest flight prices on average. 3% potential price decrease ($4 potential savings vs. average RT price).
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Average for round-trip flights in June 2025
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Price to beat on a round-trip flight from Ontario to San Francisco.
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Price to beat on a one-way flight from Ontario to San Francisco.
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Find flight deals from Ontario to San Francisco

Cheapest flights from Ontario to San Francisco
Explore the most affordable flight options available from Ontario to San Francisco. Find the lowest fares from popular airlines and budget airlines, with prices last updated on June 30, 2025.

This Kiwi.com deal was found by Cheapflights users on 6/28. 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.
Mon 7/289:41 pmONT - SFO
Nonstop1h 33mFrontier
Mon 8/410:11 pmSFO - ONT
Nonstop1h 29mFrontier
Deal found 6/28$57
This United Airlines deal was found by Cheapflights users on 6/30. 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.
Wed 7/166:39 pmONT - SFO
Nonstop1h 27mUnited Airlines
Tue 7/2210:45 amSFO - ONT
Nonstop1h 29mUnited Airlines
Deal found 6/30$106

Cheapflights Fare Finder

Customize your flight search to find flights from Ontario to San Francisco 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 June 30, 2025.
Use the filters below to find and compare flights from Ontario to San Francisco that are best for you.

Fly from

Ontario

Fly to

San Francisco

Route

Depart

Return

Price

OntarioSan Francisco

ONT - SFO

ONTSFO

Ontario

Mon 7/28

9:41 pm-11:14 pm

Nonstop1h 33m

San Francisco

Mon 8/4

10:11 pm-11:40 pm

Nonstop1h 29m

$57

OntarioSan Francisco

ONT - SFO

ONTSFO

Ontario

Mon 8/4

6:39 pm-8:06 pm

Nonstop1h 27m

San Francisco

Wed 8/6

9:25 pm-10:52 pm

Nonstop1h 27m

$97

OntarioSan Francisco

ONT - SFO

ONTSFO

Ontario

Tue 8/12

1:19 pm-2:46 pm

Nonstop1h 27m

$29

OntarioSan Francisco

ONT - SFO

ONTSFO

Ontario

Mon 7/21

9:41 pm-11:14 pm

Nonstop1h 33m

$39

OntarioSan Francisco

ONT - SFO

ONTSFO

Ontario

Mon 8/18

6:20 pm-11:20 pm

1 stop5h 00m

$76

OntarioSan Francisco

ONT - SFO

ONTSFO

Ontario

Sun 7/13

7:05 pm-11:42 pm

1 stop4h 37m

$95

Flights are sorted by cheapest round-trip flights first.

Deals found on 6/30

The best insider tips for Ontario to San Francisco 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 Ontario to San Francisco trip
Airlines
Frontier

Frontier's UpFront Plus guarantees an empty middle seat for extra comfort.


Early check-in helps secure your place onboard due to frequent overbooking.

Read more about Frontierby Marisa Garcia
United Airlines

Basic Economy allows a personal item only; no carry-on bags without extra fees.


Economy Plus offers extra legroom seats towards the front of the economy cabin.

Read more about United Airlinesby Harriet Baskas
Airports
ONT

ONT offers quick security checks compared to LAX, making it ideal for business travelers seeking a hassle-free departure.

Read more about ONTby Bill Fink
SFO

Use BART for affordable transit from SFO to downtown San Francisco, taking about 40 minutes. It's the least expensive option.

Read more about SFOby Harriet Baskas
Our travel experts
Marisa Garcia

Marisa Garcia

Expert on Frontier

Marisa Garcia

Marisa Garcia

Marisa knows planes inside and out, spending 16 years working on aircraft in hangars at airports around the world. She is an aviation industry expert, specialized in airline interiors and regulations. Ten years ago, she pivoted to journalism. She shares her insights in leading aviation, travel, and business publications and on her site FlightChic.

Read more
Harriet Baskas

Harriet Baskas

Expert on United Airlines and 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
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

Best time to book a flight from Ontario to San Francisco

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

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

Use this chart to determine the optimal time to book a round-trip flight from Ontario to San Francisco. Price data was last updated on June 27, 2025.

Booking 89 days in advance of your planned departure date is, on average, the best time to get cheap flights from Ontario to San Francisco. 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 Ontario to San Francisco?

Currently, January is the cheapest month in which you can book a flight from Ontario to San Francisco (average of $276). Flying from Ontario to San Francisco in June is currently the most expensive (average of $360). 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 SFO?

Find hourly flight availability from Ontario to San Francisco. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated June 30, 2025.

One of the essential ways to save on airfare from Ontario to San Francisco is to remain as flexible as possible. Flights that are at noon tend to be the most expensive. A flight in the evening could potentially save you up to 66% on airfare.

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

Use this chart to determine the cheapest time to fly round-trip from Ontario to San Francisco. Price data was last updated on June 29, 2025.

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

Weekly flight availability from Ontario to San Francisco

Explore weekly flight availability from Ontario to San Francisco. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated June 30, 2025.

The most flights from ONT to SFO are scheduled on a Friday (10 on average). You will have fewer flight options on Wednesday, which is when the least amount of flights are scheduled (6 on average).

Reviews of airlines servicing San Francisco

Get insights into the airlines that provide service to San Francisco. 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 San Francisco. Reviews last updated June 30, 2025.
See what other customers who have flown with Southwest, United Airlines, and American Airlines from Ontario to San Francisco have to say. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,278 reviews

Overall

8.0

Comfort

8.0

Boarding

8.2

Entertainment

7.6

Crew

8.6

Food

7.0

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Southwest
8.0
Very good
4,278 reviews
Southwest
8.0
Very good
4,278 reviews

Overall

8.0

Comfort

8.0

Boarding

8.2

Entertainment

7.6

Crew

8.6

Food

7.0

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
United Airlines
7.4
Good
8,852 reviews
Southwest
8.0
Very good
4,278 reviews

Overall

8.0

Comfort

8.0

Boarding

8.2

Entertainment

7.6

Crew

8.6

Food

7.0

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
American Airlines
7.2
Good
10,000 reviews
Southwest
8.0
Very good
4,278 reviews

Overall

8.0

Comfort

8.0

Boarding

8.2

Entertainment

7.6

Crew

8.6

Food

7.0

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Frontier
5.9
Fair
3,289 reviews
Southwest
8.0
Very good
4,278 reviews

Overall

8.0

Comfort

8.0

Boarding

8.2

Entertainment

7.6

Crew

8.6

Food

7.0

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.

Related info for your journey

Find useful and relevant information for your journey from Ontario to San Francisco. 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 Ontario to San Francisco?

    To fly from Ontario to San Francisco, you need to book a flight from Ontario (ONT) to San Francisco (SFO). Nonstop flights to San Francisco from Ontario take 1h 18m on average. When it comes time to book airfare, you have a few options: there are 8 outbound flights from Ontario to San Francisco offered by 6 different airlines.

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

    This flight path from Ontario to San Francisco was viewed by 182 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

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

    Flying on Frontier is currently your cheapest option to San Francisco, with prices starting at $57. Another option worth looking into is United Airlines, starting at $117 round trip. You may be able to fly from Ontario to San Francisco for 49% less than the average price by searching for these airlines.

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

    The cheapest airline one-way is United Airlines, with whom users have recently found tickets for as low as $29. However, be on the lookout for offers from Frontier and Southwest, as they are both options that can get you from Ontario to San Francisco for a low price.

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

    Looking for the most reliable airlines to get you to your destination on time? Our data shows these are most likely to get you from Ontario to San Francisco on time: Emirates (98%), SkyWest Airlines (92%), Air Canada (88%).

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

    On average you can expect to pay $1,765 for a flight from Ontario to San Francisco. The cheapest flight overall is $28 while the most popular route, (Ontario - San Francisco) is currently priced at $38.

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

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

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

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

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

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

    Currently, January is the cheapest month in which you can book a flight from Ontario to San Francisco (average of $276). Flying from Ontario to San Francisco in June is currently the most expensive (average of $360). 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

Traveling to a place near Ontario?

Book flights to Ontario if you plan to visit one of these locations
Roseville
Mountain View
South San Francisco
Livermore
Santa Cruz
Turlock
Manteca
Watsonville
Fairfield
Antioch
Hollister
Milpitas
Sunnyvale
Newark
Alameda
Hayward
Daly City
Campbell
Capitola
Foster City

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Alternative routes for Ontario to San Francisco

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Top 6 airlines flying from Ontario to San Francisco

Discover the top 6 airlines that operate flights from Ontario to San Francisco. 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 June 30, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$23Average$78FlexibilityNo cancel feeOn-time65%
FrontierCheapest$35Average$86FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$58Average$202FlexibilityNo cancel feeOn-time69%
Alaska AirlinesCheapest$67Average$206FlexibilityNo cancel feeOn-time75%
DeltaCheapest$85Average$197FlexibilityNo cancel feeOn-timeN/A
SouthwestCheapest$116Average$345FlexibilityNo cancel feeOn-time63%

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