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Ontario

$104+ Cheap flights from Seattle to Ontario (SEA - 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 8/3. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ONT
Jul 8 — Jul 151
Wed 7/8
Wed 7/15
1 adult, Economy
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Find cheap flights from Seattle to Ontario with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

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3. Compare prices and book

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Cheapflights Tip: The best prices from Seattle/Tacoma Intl to Ontario are usually found in October or September, booked 56 days in advance, depart on a Wednesday or Thursday and return on a Saturday

Cheap flight deals from Seattle to Ontario

Cheapest flights from Seattle to Ontario
Explore the most affordable flight options available from Seattle to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on June 8, 2026.

This CheapOair deal was found by Cheapflights users on 6/3. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/18:13 pm
SEA
-
ONT
1 stop23h 35m
Frontier
Thu 9/34:04 pm
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 6/3$168
This Frontier deal was found by Cheapflights users on 6/3. 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 9/2211:15 am
SEA
-
ONT
Nonstop2h 48m
Frontier
Tue 9/225:05 pm
ONT
-
SEA
Nonstop2h 56m
Frontier
Deal found 6/3$173
This Frontier deal was found by Cheapflights users on 6/4. 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.
Mon 8/38:53 pm
SEA
-
ONT
1 stop11h 10m
Frontier
Tue 8/44:09 pm
ONT
-
SEA
Nonstop2h 49m
Frontier
Deal found 6/4$174
This Super.com deal was found by Cheapflights users on 6/7. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/1911:53 am
SEA
-
ONT
Nonstop2h 46m
Frontier
Tue 8/254:04 pm
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 6/7$175
This Super.com deal was found by Cheapflights users on 6/7. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/2211:53 am
SEA
-
ONT
Nonstop2h 46m
Frontier
Wed 8/264:04 pm
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 6/7$176
This Super.com deal was found by Cheapflights users on 6/8. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/3011:15 am
SEA
-
ONT
Nonstop2h 48m
Frontier
Sat 10/35:05 pm
ONT
-
SEA
Nonstop2h 56m
Frontier
Deal found 6/8$177
This Frontier deal was found by Cheapflights users on 6/4. 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 9/111:53 am
SEA
-
ONT
Nonstop2h 46m
Frontier
Sat 9/54:04 pm
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 6/4$178
This CheapOair deal was found by Cheapflights users on 6/6. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/318:13 pm
SEA
-
ONT
1 stop23h 35m
Frontier
Wed 9/24:04 pm
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 6/6$184
This Super.com deal was found by Cheapflights users on 6/7. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/511:53 am
SEA
-
ONT
Nonstop2h 46m
Frontier
Sun 9/64:04 pm
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 6/7$185
This Super.com deal was found by Cheapflights users on 6/7. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/2611:53 am
SEA
-
ONT
Nonstop2h 46m
Frontier
Mon 8/314:04 pm
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 6/7$186
This Frontier deal was found by Cheapflights users on 6/6. 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.
Sun 8/1612:26 pm
SEA
-
ONT
Nonstop2h 55m
Frontier
Tue 8/254:04 pm
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 6/6$188
This Frontier deal was found by Cheapflights users on 6/6. 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 8/1112:26 pm
SEA
-
ONT
Nonstop2h 55m
Frontier
Wed 9/24:04 pm
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 6/6$189

Find flight deals from Seattle to Ontario

Discover tips and strategies to find the most affordable flight options for your journey from Seattle (SEA) 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 June 8, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$168
(CheapOair)

One-way from

$104
(Kiwi.com)

Popular in

February

Cheapest in

October

Average price

$233

Good round-trip deal

$203 or less

Good one-way deal

$130 or less
Provider with most accurate pricing for Seattle/Tacoma Intl-Ontario flight deals.
Search Deals
Provider most trusted by Cheapflights users for Seattle/Tacoma Intl-Ontario flights.
Search Deals
From Seattle/Tacoma Intl to Ontario
Search Deals
One-way flight from Seattle/Tacoma Intl to Ontario
Search Deals
Highest demand for flights based on searches. 13% potential increase in price ($40 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($10 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in June 2026
Search Deals
Price to beat on a round-trip flight from Seattle/Tacoma Intl to Ontario.
Search Deals
Price to beat on a one-way flight from Seattle/Tacoma Intl to Ontario.
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Seattle 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 June 8, 2026.
Use the filters below to find and compare flights from Seattle to Ontario that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 9/1

6:25 am-1:35 pm

2 stops7h 10m

Ontario

Sat 9/5

1:00 pm-9:30 pm

1 stop8h 30m

$242

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 8/29

11:35 am-6:20 pm

1 stop6h 45m

Ontario

Wed 9/2

1:10 pm-8:15 pm

2 stops7h 05m

$252

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 7/14

5:59 pm-11:48 pm

1 stop5h 49m

Ontario

Mon 7/20

6:20 am-9:15 am

Nonstop2h 55m

$337
Quickest round-trip

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 7/18

10:12 am-3:38 pm

1 stop5h 26m

Ontario

Sun 7/19

9:20 pm-11:59 pm

Nonstop2h 39m

$337

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Wed 8/12

4:10 pm-8:55 pm

1 stop4h 45m

Ontario

Sun 8/16

6:40 am-2:00 pm

2 stops7h 20m

$352

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Fri 8/14

3:30 pm-8:01 pm

1 stop4h 31m

Ontario

Tue 9/1

9:01 am-2:24 pm

1 stop5h 23m

$370

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 7/28

7:30 am-5:05 pm

2 stops9h 35m

Ontario

Sat 8/1

4:55 pm-1:15 am

2 stops8h 20m

$412

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 7/14

5:20 pm-10:37 pm

1 stop5h 17m

Ontario

Tue 7/21

6:00 am-12:34 pm

1 stop6h 34m

$427

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Fri 9/4

9:50 am-5:10 pm

2 stops7h 20m

Ontario

Sun 9/6

6:05 pm-10:39 pm

1 stop4h 34m

$447

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 8/15

10:12 am-3:38 pm

1 stop5h 26m

Ontario

Tue 8/18

7:00 am-2:59 pm

2 stops7h 59m

$462

Flights are sorted by cheapest round-trip flights first.

Deals found on 6/3

Showing 1-10 of 22 resultsSorted by cheapest first
1
2
3

Compare providers for flights from Seattle to Ontario

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Seattle to Ontario in June.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy1 starTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*3 stars
CheapflightsfaresPrice Accuracy2 starsTrust Score*1 star
CheapOairPrice Accuracy3 starsTrust Score*3 stars
eDreamsPrice Accuracy2 starsTrust Score*3 stars
JetabroadPrice Accuracy3 starsTrust Score*3 stars
Kiwi.comPrice Accuracy3 starsTrust Score*3 stars
Justfly.comPrice Accuracy3 starsTrust Score*3 stars
MytripPrice Accuracy2 starsTrust Score*3 stars
Super.comPrice Accuracy-Trust Score*3 stars

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on Seattle-Ontario flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Seattle-Ontario flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Seattle-Ontario flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Seattle-Ontario flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Seattle-Ontario flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

Best time to book a flight from Seattle to Ontario

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

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

The best time to book flights from Seattle to Ontario is 55 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.

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

Currently, October is the cheapest month in which you can book a flight from Seattle to Ontario (average of $187). Flying from Seattle to Ontario in February is currently the most expensive (average of $377). 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 SEA to ONT?

Find hourly flight availability from Seattle 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 June 8, 2026.

A simple way to save on the total cost of your ticket is to fly from Seattle to Ontario at noon. If you’re flexible enough to do this you can expect to save up to 29% on your trip compared to booking a flight in the afternoon.

What is the cheapest day to fly from Seattle to Ontario?

Use this chart to determine the cheapest time to fly round-trip from Seattle to Ontario. Price data was last updated on May 30, 2026.

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

How much does it cost to fly round-trip from Seattle to Ontario?

The best insider tips for Seattle to Ontario flights

AI-powered summary based on content written by travel experts. AI can make mistakes.
Cheapflights partnered with top experts to bring you the best recommendations for your Seattle to Ontario trip
Our travel experts
Robert Schrader

Robert Schrader

Expert on Alaska Airlines

One of the web's original travel bloggers, Robert launched his first site Leave Your Daily Hell in 2009. Since then, he's expanded into destination niche sites (one each for Japan, Thailand and Taiwan), in addition to having written for the inflight magazines of Singapore Airlines and Korean Air. Overall, he's visited nearly 100 countries, and flies business as often as possible.

Read more
Marisa Garcia

Marisa Garcia

Expert on Frontier

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
Bill Fink

Bill Fink

Expert on ONT

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
Brandon Schultz

Brandon Schultz

Expert on SEA

Brandon Schultz is an award-winning food and travel writer based in New York City. His work has appeared in Forbes, AAA, Thrillist, Travel + Leisure, and The Daily Meal, among many others, and he is the author of 6 books, including 3 cookbooks.

Read more

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 June 8, 2026.
See what other customers who have flown with Alaska Airlines,Southwest, andDelta from Seattle to Ontario have to say. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
7.9
Good
12,481 reviews

Boarding

8.1

Overall

7.9

Crew

8.5

Food

7.1

Comfort

7.8

Entertainment

7.0

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2026

SEA - RNO

There was a delay and my husband needs a wheelchair and we were moved from 1 gate to another.
Alaska Airlines
7.9
Good
12,481 reviews
Alaska Airlines
7.9
Good
12,481 reviews

Boarding

8.1

Overall

7.9

Crew

8.5

Food

7.1

Comfort

7.8

Entertainment

7.0

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2026

SEA - RNO

There was a delay and my husband needs a wheelchair and we were moved from 1 gate to another.
Southwest
7.9
Good
4,246 reviews
Alaska Airlines
7.9
Good
12,481 reviews

Boarding

8.1

Overall

7.9

Crew

8.5

Food

7.1

Comfort

7.8

Entertainment

7.0

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2026

SEA - RNO

There was a delay and my husband needs a wheelchair and we were moved from 1 gate to another.
Delta
7.9
Good
8,395 reviews
Alaska Airlines
7.9
Good
12,481 reviews

Boarding

8.1

Overall

7.9

Crew

8.5

Food

7.1

Comfort

7.8

Entertainment

7.0

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2026

SEA - RNO

There was a delay and my husband needs a wheelchair and we were moved from 1 gate to another.
Hawaiian Airlines
7.8
Good
2,830 reviews
Alaska Airlines
7.9
Good
12,481 reviews

Boarding

8.1

Overall

7.9

Crew

8.5

Food

7.1

Comfort

7.8

Entertainment

7.0

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2026

SEA - RNO

There was a delay and my husband needs a wheelchair and we were moved from 1 gate to another.
Frontier
5.6
Fair
2,904 reviews
Alaska Airlines
7.9
Good
12,481 reviews

Boarding

8.1

Overall

7.9

Crew

8.5

Food

7.1

Comfort

7.8

Entertainment

7.0

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2026

SEA - RNO

There was a delay and my husband needs a wheelchair and we were moved from 1 gate to another.

Related info for your journey

Find useful and relevant information for your journey from Seattle 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 Seattle to Ontario?

    Booking a flight from Seattle/Tacoma Intl (SEA) to Ontario (ONT) is your only option if you wish to fly from Seattle to Ontario. On a typical day, there are 8 flights from Seattle/Tacoma Intl to Ontario, all of which are around 2h 38m for a nonstop flight. You can also purchase a plane ticket from 5 airlines when you book a flight from Seattle/Tacoma Intl to Ontario.

  • How popular is this Seattle to Ontario flight route?

    This flight path from Seattle/Tacoma Intl to Ontario was viewed by 44 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

  • How long is the flight from Seattle to Ontario?

    A quick flight from Seattle to Ontario can take about 5h 26m. Southwest provides one of the quickest options available for as low as $337. The distance from Seattle to Ontario is about 956 mi. Both multi-stop and nonstop flights can be found to your destination and back.

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

    Our cheapest airline available from Seattle to Ontario is Frontier. Our recent data shows that you can find tickets from as low as $77 on this airline. Additional options worth looking into are Hawaiian Airlines and Delta, starting at $98 and $110 round-trip. Frontier is priced at 70% lower than the current average price of a flight leaving 3 months from now.

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

    For one-way options, check prices for Frontier. According to our data, you can fly for as low as $55. Users have also found prices from $62 and $80 on Southwest and Delta, respectively.

  • What are the most reliable airlines from Seattle to Ontario?

    Before booking your flight to Ontario from Seattle, check out the most reliable airlines to get you to your destination on time: Frontier (100%), Volaris (100%), SkyWest Airlines( 92%).

  • What are the cheapest flights from Seattle to Ontario?

    Looking at all options, your cheapest flight can be booked for $74. While the most popular route (Seattle/Tacoma Intl - Ontario) can be booked for $173 on average, our data indicates $242 when flying from Seattle to Ontario.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Seattle 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 Seattle to Ontario?

    Currently, October is the cheapest month in which you can book a flight from Seattle to Ontario (average of $187). Flying from Seattle to Ontario in February is currently the most expensive (average of $377). 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 Seattle to Ontario

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Top 5 airlines flying from Seattle to Ontario

Discover the top 5 airlines that operate flights from Seattle 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 June 8, 2026.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$76Average$206FlexibilityNo cancel feeOn-time62%
Hawaiian AirlinesCheapest$98Average$319FlexibilityNo cancel feeOn-time85%
DeltaCheapest$111Average$275FlexibilityNo cancel feeOn-timeN/A
SouthwestCheapest$130Average$246FlexibilityNo cancel feeOn-time63%
Alaska AirlinesCheapest$137Average$307FlexibilityNo cancel feeOn-time75%

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