ONT - SFO

$68 Find Cheap Flights from Ontario to San Francisco

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Ontario to San Francisco departing on 4/15. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

KAYAK searches hundreds of travel sites at once for deals on flights to San Francisco

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Ontario to San Francisco, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Ontario to San Francisco, as well as popular online travel agencies
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Everything you should know

Cheapest round-trip
$115
Typical prices: $158-$68
Frontier
Wed 5/13Wed 5/20
ONT - SFO • Non-stop
Cheapest one-way
$69
Typical prices: $58-$116
Frontier
Wed 4/15
ONT - SFO • 1 stop
Advice from real travelers
AI-powered summary based on content written by travel experts. AI can make mistakes.
United's Economy Plus offers extra legroom benefits.
ONT's streamlined security makes it a quick start.
Expert advice
Expert advice
Expert advice
Expert advice
Top airlines
Cheapest • from $115 (round-trip)
Best reviews • 8.0 score
Airline reviews
Airline reviews
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Airline reviews
Airline reviews
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Nonstop flights
You can fly direct with Frontier and United Airlines. Average duration is 1h 33m
Direct flights
Direct flights
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Direct flights
Direct flights
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When to book
in advance
Our data shows that travelers who book at least 2 weeks in advance save around 24% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
Cheapest • 46% price drop
Most popular
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Start a new search
KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to San Francisco!
Flight Deals
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Flight Deals

Cheap Flights from Ontario to San Francisco (ONT-SFO)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Ontario to San Francisco that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Ontario to San Francisco

Wed, May 13 - Wed, May 20
Frontier Logo
8:17 pm - 9:55 pm
ONT
-
SFO
1h 38mnonstop
Frontier Logo
11:26 am - 1:05 pm
SFO
-
ONT
1h 39mnonstop
$115Frontier
Tue, May 5 - Wed, May 6
Frontier Logo
8:17 pm - 9:55 pm
ONT
-
SFO
1h 38mnonstop
Frontier Logo
11:26 am - 1:05 pm
SFO
-
ONT
1h 39mnonstop
$116Frontier
Tue, Jun 9 - Wed, Jun 10
Frontier Logo
8:33 pm - 10:05 pm
ONT
-
SFO
1h 32mnonstop
Frontier Logo
11:12 am - 12:42 pm
SFO
-
ONT
1h 30mnonstop
$117Frontier
Sun, Jun 7 - Tue, Jun 9
Frontier Logo
3:30 pm - 8:49 am
ONT
-
SFO
17h 19m
1 stop
Frontier Logo
11:12 am - 12:42 pm
SFO
-
ONT
1h 30mnonstop
$122Frontier
Thu, May 14 - Wed, May 20
Frontier Logo
8:17 pm - 9:55 pm
ONT
-
SFO
1h 38mnonstop
Frontier Logo
11:26 am - 1:05 pm
SFO
-
ONT
1h 39mnonstop
$127Frontier
Sat, May 9 - Tue, May 12
Frontier Logo
9:15 am - 11:04 pm
ONT
-
SFO
13h 49m
1 stop
Frontier Logo
11:26 am - 1:05 pm
SFO
-
ONT
1h 39mnonstop
$128Frontier
Wed, May 6 - Sat, May 9
Frontier Logo
8:17 pm - 9:55 pm
ONT
-
SFO
1h 38mnonstop
Frontier Logo
6:00 am - 11:49 pm
SFO
-
ONT
17h 49m
1 stop
$129Frontier
Tue, May 12 - Wed, May 13
Frontier Logo
8:17 pm - 9:55 pm
ONT
-
SFO
1h 38mnonstop
Frontier Logo
11:26 am - 1:05 pm
SFO
-
ONT
1h 39mnonstop
$135Frontier
Thu, May 7 - Sat, May 9
Frontier Logo
8:17 pm - 9:55 pm
ONT
-
SFO
1h 38mnonstop
Frontier Logo
9:19 am - 10:51 am
SFO
-
ONT
1h 32mnonstop
$138Frontier
Thu, Apr 30 - Sun, May 3
Frontier Logo
9:10 am - 10:50 am
ONT
-
SFO
1h 40mnonstop
Frontier Logo
8:53 am - 8:04 am
SFO
-
ONT
23h 11m
1 stop
$139Frontier
Booking Insights

KAYAK's insights & trends for Ontario to San Francisco flights

Get data-powered insights and trends into flights from Ontario to San Francisco to help you find the cheapest flights, the best time to fly and much more.

How much is a round-trip flight from Ontario to San Francisco?

This analysis is based on the cheapest round-trip price found on KAYAK in the last 12 months by searching for a flight from Ontario to San Francisco departing in May.

What’s the cheapest day of the week to fly from Ontario to San Francisco?

The average price of all round-trip flights from Ontario to San Francisco clicked on KAYAK for each day over the last 12 months.

For Ontario to San Francisco, Friday is the cheapest day to fly on average and Monday is the most expensive. Flying from San Francisco back to Ontario, the best deals are generally found on Monday, with Tuesday being the most expensive.

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Ontario to San Francisco, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Ontario to San Francisco is May, where tickets cost $96 (return) on average. On the other hand, the most expensive months are February and January, where the average cost of round-trip tickets is $298 and $270 respectively.

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

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Ontario to San Francisco, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from Ontario to San Francisco, you should book around 2 weeks before departure, which saves you about 24% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 18 weeks before departure.

Expert advice

Expert advice for your flight from Ontario to San Francisco

 
AI-powered summary based on content written by travel experts. AI can make mistakes.
KAYAK teamed up with top travel experts to share the best tips for your journey.
Our travel experts
Stefanie Waldek

Stefanie Waldek

Expert on United Airlines and Frontier

Stefanie Waldek is a freelance space, travel, and design writer based in Saratoga Springs, NY. Her words have appeared in Space.com, Travel + Leisure, Condé Nast Traveler, Architectural Digest, and House Beautiful, among other publications. An expert in aviation and expedition cruising, Stefanie is frequently up in the air or on the sea, likely en route to Antarctica or the Arctic.

Jennifer Simonson

Jennifer Simonson

Expert on ONT

Jennifer Simonson is driven by her lifelong commitment to exploring the globe. Her insatiable curiosity had led her to immerse herself into diverse locations like Oklahoma City and Pismo. Her hotel recommendations are the result of the myriad hotels she's stayed at across her travels. Along her journey, she cherishes engaging conversations with locals, indulging in the finest ice cream, trying her hand at surfing, and embarking on nature-filled hikes.

Blane Bachelor

Blane Bachelor

Expert on SFO

Blane Bachelor is a journalist and editor specializing in travel and aviation who writes regularly for top global outlets. Born and raised in Florida, Blane has worked and lived in four countries, including the Netherlands, where she’s currently based with her family. Her favorite way to get to know a new destination is by running or riding a bike around town – or hearing a spooky ghost story about local history. She will always choose the window seat.

Good to know

Low seasonJanuary
Cheapest flight$69
Best time to beat the crowds but there is an average 52% increase in price.
Most popular time to fly and prices are also 46% lower on average.
Flight from Ontario to San Francisco

When to book flights from Ontario to San Francisco

Are your dates flexible? Find out the best times to travel from Ontario to San Francisco based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking flights from Ontario to San Francisco

  • What is the cheapest flight from Ontario to San Francisco?

    In the last 3 days, the lowest price for a flight from Ontario to San Francisco was $69 for a one-way ticket and $115 for a round-trip.

  • Do I need a passport to fly between Ontario and San Francisco?

    A passport is not required to fly from Ontario to San Francisco.

  • Which airlines offer Wi-Fi service onboard planes from Ontario to San Francisco?

    Alaska Airlines, Delta, Japan Airlines, American Airlines, and British Airways offer inflight Wi-Fi service on the Ontario to San Francisco flight route.

  • Which aircraft models fly most regularly from Ontario to San Francisco?

    The Boeing 737 MAX 9 is the aircraft model that flies most regularly on the Ontario to San Francisco flight route.

  • Which airline alliances offer flights from Ontario to San Francisco?

    oneworld, and Star Alliance are the airline alliances operating flights between Ontario and San Francisco, with oneworld being the most commonly used for this route.

  • On which days can I fly direct from Ontario to San Francisco?

    There are nonstop flights from Ontario to San Francisco on a daily basis.

  • Which is the best airline for flights from Ontario to San Francisco, Southwest or Alaska Airlines?

    The two airlines most popular with KAYAK users for flights from Ontario to San Francisco are Southwest and Alaska Airlines. With an average price for the route of $332 and an overall rating of 8.0, Southwest is the most popular choice. Alaska Airlines is also a great choice for the route, with an average price of $173 and an overall rating of 7.9.

  • How does KAYAK find such low prices on flights from Ontario to San Francisco?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Ontario to San Francisco.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Ontario to San Francisco?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to San Francisco from Ontario is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Ontario to San Francisco?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to San Francisco with an airline and back to Ontario with another airline. Booking your flights between Ontario and SFO can sometimes prove cheaper using this method.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Ontario to San Francisco?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to San Francisco from Ontario up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

KAYAK’s top tips for finding a cheap flight from Ontario to San Francisco

  • Looking for a cheap flight? 25% of our users found flights on this route for $116 or less one-way and $224 or less round-trip.

Prefer to fly direct from Ontario to San Francisco?

 
Direct data is based off flight results for the next 60 days. Find direct flights from all airlines flying direct from Ontario to San Francisco.
Find which airlines fly direct from Ontario Airport to San Francisco Airport, which days they fly and book direct flights.

Direct departures

Ontario to San Francisco

Monday

Frontier,United Airlines

Frontier,United Airlines

Tuesday

United Airlines,Frontier

United Airlines,Frontier

Wednesday

United Airlines,Frontier

United Airlines,Frontier

Thursday

Frontier,United Airlines

Frontier,United Airlines

Friday

Frontier,United Airlines

Frontier,United Airlines

Saturday

United Airlines,Frontier

United Airlines,Frontier

Sunday

Frontier,United Airlines

Frontier,United Airlines

See more direct flights

Direct returns

San Francisco to Ontario

Monday

Frontier,United Airlines

Frontier,United Airlines

Tuesday

United Airlines,Frontier

United Airlines,Frontier

Wednesday

United Airlines,Frontier

United Airlines,Frontier

Thursday

Frontier,United Airlines

Frontier,United Airlines

Friday

Frontier,United Airlines

Frontier,United Airlines

Saturday

United Airlines,Frontier

United Airlines,Frontier

Sunday

Frontier,United Airlines

Frontier,United Airlines

See more direct flights

Reviews of the top 4 airlines serving from Ontario to San Francisco

 
See real verified KAYAK customer reviews for airlines flying from Ontario to San Francisco. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Ontario to San Francisco? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
SouthwestOverall score based on 4334 reviews
7.0Food
7.5Entertainment
8.0Comfort
8.6Crew
8.1Boarding
Airline reviews

Boarding was easy. The seats are small and fairly uncomfortable

8.0 ExcellentNicole, Mar 2026
LGB - OAK
Read more Southwest reviews

Boarding was easy. The seats are small and fairly uncomfortable

The problem with the seat assignments is that there were a lot of rows in the front that were empty but my row at the back was full. Just not so pleasant.

No food or entertainment, just a quick 40 minute flight. A little bumpy due to Santa Ana winds but pilot has no control over that. Good flight and landing!

Good but I prefer choose your own seat. With the new assigned seats they should board from the back I see no advantage to this new boarding. Just like every other airline

Mediocre. Boarding is now unpleasant. The employees, once friendly and nice, are now regularly speaking sternly to passengers, badgering them to do things right so they can take off on time and gate check bags because they don't have enough overhead bin space. The pretzel snack was crushed flat and broken into even smaller pieces, which happens frequently lately. Drink service was suspended before they reached my row.

The charges were ridiculous for an hour flight and the turbulence was very scary.

3 hour delay. Had to change plans and was still delayed.

The flight crew was extremely rude and especially not helpful when our flight was delayed.

The boarding and seat assignment system no longer works for me, but I know it is being replaced. Otherwise, I am good with the overall experience.

The lead steward kept singing about "San Francisco" and hotel California---more annoying than humorous....needs work. Flight was smooth and on time.

i canceled my flight from SEA to SFO, SNA to SEA and received full refund from Alaska Airlines. i am pleased with the customer service.

i canceled my return flight package with Alaska Airlines. Customer Service was excellent and assisted me to cancelled both of our reservations and returned the payment in full. that is excellent service and understanding and empathy of the customers' needs. i like Alaska Airlines and recommend AS to everyone.

Representatives both at the gate and on the plane have zero interest in helping you! It’s really unfortunate…

I was in economy class and there was plenty of leg room. New interior which was nice and they served various kinds of chips and sodas on the red eye. You couldn't get a bottle of water but they instead served it in a medium paper cup from a reinforced structured paper container, environmental friendly.

Great experience, staff and crew were very professional, friendly and helpful!

I fell asleep and missed my flight and they rescheduled me no problem. Staff was professional and the plane was clean. I was very happy with my experience.

Alaska used to be a top notch airline. With it's growth it is now in line with the big airlines. Not bad, not great.

Overall it was fine, however one of my two checked bags did not arrive and I was told it was left in Palm Springs. I don't understand how one of the two bags made it through fine but the other got lost .

The seats are very small. I’m 5’ 3”, so don’t think I should notice. The food selection was non existent and very disappointing. 5 hour flight plus TSA, etc. I would have appreciated a small salad, crudités. Something fresher not just chips.

Was notified the departure would be late. Later on it was suddenly on time. Traffic by LAX was horrendous, and I missed the flight.

Horrible service no Wi-Fi connection on both leg of the flight and they are refusing to fix bad service

I will never fly ANA again. They lost one of my large pieces of checked luggage, the heaviest one with the most valuable items in it, and they said they will not send me an email unless they can't find it, even though the paper they gave me to track the status of my lost luggage requires a code from an email they are supposed to send me so I can do baggage tracing. They claim to be an international airline, but they also insist on calling a Japanese telephone number to confirm where to send the lost baggage if they find it. It is impossible to find an actual contact email address for customer support on their website, and their AI chatbot is unhelpful, directing you to a webpage that says it is for contact information but does not have any actual email addresses or phone numbers listed on it. My seat in economy did not recline at all, even though I was not sitting in an exit row nor the very back row. I had to sit in the fully upright position for over ten hours of international travel. Awful experience overall.

Overall we had a good experience during our flight from San Francisco to Houston.

the whole trip was smooth, and as comfortable as flying is these days. flight crew was friendly and very courteous and helpful.

First class ticket gets you a choice of chips or nuts. . Just like economy Southwest. Also no screen in the seats. This is first class???!

Flight arrived 30 min early and bag was waiting at the baggage pickup. United Club HNL was one of the nicest in the system

Yet another flight in which beverage and snack service was skipped. Other that that, firmly mediocre. Landed early, to gate late due to congestion at the gates. Airline's fault or airports fault: unknown.

Teeny tiny bathrooms, crew was not realistic about when we'd arrive.

Flight was late - I was downgraded from first class to coach

United needs to step up their game. Delayed flight leaving Seattle, San Francisco. Older aircraft, not very comfortable.

Remind customers of the need to have passport or new ID for boarding.

The flight never took off and we spent 7 hours at the airport

Our flight was canceled. I will never use Kayak nor Frontier for travel again. The entire experience was a headache.

It was ok. It was expensive to check 2 bags ($75.00 per bag), and then it took a long time to wait for shuttle to take us from one terminal to the terminal where the plane was taking off at LAX. And all of this for a flight where we had to pay for any food or drink that was not water.

When I wanted to check in 3 hours prior to boarding time, the employees mentioned “a little over an hour delay” so I waited for an hour then I went to go look for food in the terminal and most people from that flight were in the same area looking for food. Finally I decided after food to check to see if it’s anytime closer and now it’s 2 mins until boarding closes?! What are you kidding me? I didn’t receive anything via sms about boarding now nor via email or on the intercom. I luckily made it through, barely, and then there’s no room for my carry on mind you I’m in the very first row so I had to place my purse in one further row back and my carry on sections down. Not sure who pays for better seats to get your stuff placed all over the plane but that was the worst experience I’ve ever had flying with anyone.

Terrible. The canceled my entire flight when I requested a refund for a trip frontier canceled trip one way.

i was unable to check in the flight. refund requested

I think Frontier was very good at communication. Their app worked very well. Loading was great and the flight was nice and easy.

This airline sucks. They offer low rates then charge you for everything, the app does not work well, the seats are the most uncomfortable. Maintenance issues on the flight, and you still have to sit through their credit card commercials. People are nice enough but does not make up for overall poor experience.

Great for the price. No wifi or entertainment, but gate agents and crew were fantastic and we boarded quickly and left on time.

Everything you need to know for your flight from Ontario to San Francisco

Other airlines flying from Ontario to San Francisco

Flights from the other most popular airlines that fly from Ontario to San Francisco according to KAYAK users. Prices are the lowest found on KAYAK over the last 7 days. Price and availability are not guaranteed.