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Cheap flights from Seattle to Ontario from C$ 122

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 4/9. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ONT
2 Aug — 9 Aug1
1 adult

Cheapflights Tip: The best prices from Seattle/Tacoma Intl to Ontario are usually found in September or August, booked 72 days in advance, depart on a Saturday or Tuesday and return on a Saturday

Cheap 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 28 July 2025.

Round-trip from

C$ 227

One-way from

C$ 122

Popular in

December

Cheapest in

September

Average price

C$ 340

Good one-way deal

C$ 268 or less
Frontier
  • Frontier
  • 19/8-25/8
  • 1 total stop
  • 10h 07m total
  • Seattle to Ontario
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United Airlines
  • United Airlines
  • 4/9
  • 1 total stop
  • 4h 32m total
  • Seattle to Ontario
Search Deals
Highest demand for flights based on searches. 7% potential increase in price (C$ 30 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease (C$ 11 potential savings vs. average RT price).
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Average for round-trip flights in July 2025
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Price to beat on a one-way flight from Seattle/Tacoma Intl to Ontario.
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Find 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 28 July 2025.

Wed 6/81:42 p.m.SEA - ONT
Nonstop2h 54mFrontier
Thu 14/810:03 a.m.ONT - SEA
Nonstop2h 50mFrontier
Deal found 27/7C$ 219
Tue 4/116:15 p.m.SEA - ONT
Nonstop2h 38mAlaska Airlines
Tue 11/116:00 a.m.ONT - SEA
Nonstop2h 50mAlaska Airlines
Deal found 27/7C$ 242
Sat 6/98:05 a.m.SEA - ONT
Nonstop2h 45mDelta
Sun 7/911:40 a.m.ONT - SEA
Nonstop2h 45mDelta
Deal found 28/7C$ 256
Thu 11/95:00 a.m.SEA - ONT
2 stops7h 40mSouthwest
Wed 17/92:10 p.m.ONT - SEA
1 stop5h 45mSouthwest
Deal found 28/7C$ 290
Mon 3/115:20 p.m.SEA - ONT
1 stop5h 25mUnited Airlines
Fri 7/116:38 p.m.ONT - SEA
1 stop4h 37mUnited Airlines
Deal found 27/7C$ 338

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 629,999 searches. Data last updated 28 July 2025.
Use the filters below to find and compare flights from Seattle to Ontario that are best for you.

Fly from

Seattle

Fly to

Ontario

Route

Depart

Return

Price

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 19/8

8:42 p.m.-11:24 p.m.

Nonstop2h 42m

Ontario

Mon 25/8

5:09 p.m.-12:34 a.m.

1 stop7h 25m

C$ 227

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 4/11

6:15 p.m.-8:53 p.m.

Nonstop2h 38m

Ontario

Tue 11/11

6:00 a.m.-8:50 a.m.

Nonstop2h 50m

C$ 242

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 6/9

8:05 a.m.-10:50 a.m.

Nonstop2h 45m

Ontario

Sun 7/9

11:40 a.m.-2:25 p.m.

Nonstop2h 45m

C$ 256

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Thu 11/9

5:00 a.m.-12:40 p.m.

2 stops7h 40m

Ontario

Wed 17/9

2:10 p.m.-7:55 p.m.

1 stop5h 45m

C$ 290

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Mon 3/11

1:20 p.m.-5:34 p.m.

1 stop4h 14m

Ontario

Mon 10/11

6:38 p.m.-11:15 p.m.

1 stop4h 37m

C$ 338

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Wed 13/8

5:25 a.m.-9:23 a.m.

1 stop3h 58m

Ontario

Wed 20/8

6:00 a.m.-8:45 a.m.

Nonstop2h 45m

C$ 352

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Thu 4/9

1:05 p.m.-5:37 p.m.

1 stop4h 32m

C$ 122

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 26/8

5:20 a.m.-9:26 a.m.

1 stop4h 06m

C$ 134

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 23/8

1:30 p.m.-6:00 p.m.

1 stop4h 30m

C$ 136

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 23/8

8:05 a.m.-10:50 a.m.

Nonstop2h 45m

C$ 149

Flights are sorted by cheapest round-trip flights first.

Deals found on 28/7

Showing 1-10 of 12 results
1
2

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?

Use this chart to determine the optimal time to book a round-trip flight from Seattle to Ontario. Price data was last updated on 25 July 2025.

Booking 72 days in advance of your planned departure date is, on average, the best time to get cheap flights from Seattle 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 Seattle to Ontario?

Currently, September is the cheapest month in which you can book a flight from Seattle to Ontario (average of C$ 290). Flying from Seattle to Ontario in December is currently the most expensive (average of C$ 461). 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 28 July 2025.

One of the essential ways to save on airfare from Seattle to Ontario is to remain as flexible as possible. Flights that are in the evening tend to be the most expensive. A flight at noon could potentially save you up to 58% on airfare.

Weekly flight availability from Seattle to Ontario

Explore weekly flight availability from Seattle to Ontario. 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 28 July 2025.

The most flights from SEA to ONT are scheduled on a Monday (27 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (17 on average).

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 28 July 2025.
Read reviews from past customers who have flown Alaska Airlines,Southwest, andDelta from Seattle to Ontario. 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.
Alaska Airlines
8.0
Very good
10,000 reviews
Check prices

Food

7.1

Overall

8.0

Crew

8.5

Entertainment

7.1

Comfort

7.8

Boarding

8.1

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews
Check prices

Food

7.1

Overall

8.0

Crew

8.5

Entertainment

7.1

Comfort

7.8

Boarding

8.1

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
Southwest
8.0
Very good
4,238 reviews
Alaska Airlines
8.0
Very good
10,000 reviews
Check prices

Food

7.1

Overall

8.0

Crew

8.5

Entertainment

7.1

Comfort

7.8

Boarding

8.1

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
Delta
8.0
Very good
7,975 reviews
Alaska Airlines
8.0
Very good
10,000 reviews
Check prices

Food

7.1

Overall

8.0

Crew

8.5

Entertainment

7.1

Comfort

7.8

Boarding

8.1

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
Hawaiian Airlines
7.8
Good
2,604 reviews
Alaska Airlines
8.0
Very good
10,000 reviews
Check prices

Food

7.1

Overall

8.0

Crew

8.5

Entertainment

7.1

Comfort

7.8

Boarding

8.1

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.
United Airlines
7.4
Good
8,892 reviews
Alaska Airlines
8.0
Very good
10,000 reviews
Check prices

Food

7.1

Overall

8.0

Crew

8.5

Entertainment

7.1

Comfort

7.8

Boarding

8.1

Reviews

1 / 20
10.0
Excellent

Jonathan,Jul 2025

SEA - BOS

Fantastic Check-in with easy baggage drop. While it took a while to find out which was the gate, the boarding was a dream, the stewards were simply incredible and the flight fantastic.

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?

    To fly from Seattle to Ontario, you need to book a flight from Seattle/Tacoma Intl (SEA) to Ontario (ONT). Nonstop flights to Ontario from Seattle/Tacoma Intl take 2h 42m on average. When it comes time to book airfare, you have a few options: there are 20 outbound flights from Seattle/Tacoma Intl to Ontario offered by 2 different airlines.

  • How popular is this Seattle to Ontario flight route?

    Within the past month, 19 users have taken a look at flights from Seattle/Tacoma Intl to Ontario.

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

    Cheapflights users have booked flights from Seattle to Ontario round-trip from C$ 227. Other airlines that can offer you cheap pricing are Alaska Airlines, from C$ 242, and Delta, from C$ 256. Frontier is currently priced 19% below the average price you’ll pay for this route.

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

    C$ 122 is the cheapest one-way deal found within the past few days, from United Airlines. You may also be able to find cheap deals on Alaska Airlines and Southwest, with prices starting from C$ 134 and C$ 136, respectively.

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

    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 Seattle to Ontario on time: Aeromexico (100%), Virgin Atlantic (94%), KLM (92%).

  • What are the cheapest flights from Seattle to Ontario?

    Looking for the cheapest flight from Seattle to Ontario? While on average our users pay C$ 268, our data indicates the cheapest price to be C$ 268. The most popular route (Seattle/Tacoma Intl - Ontario), is priced around C$ 133.

  • 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, September is the cheapest month in which you can book a flight from Seattle to Ontario (average of C$ 290). Flying from Seattle to Ontario in December is currently the most expensive (average of C$ 461). 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 2 airlines flying from Seattle to Ontario

Discover the top 2 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 629,999 searches. Data last updated 28 July 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapestC$ 96AverageC$ 134FlexibilityNo cancel feeOn-time62%
Search Frontier flights
Alaska AirlinesCheapestC$ 214AverageC$ 301FlexibilityNo cancel feeOn-time75%
Search Alaska Airlines flights

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travelers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from Seattle to Ontario?

When you search for this flight from Seattle to Ontario, Cheapflights searches on 900+ travel sites to save you time finding great flight deals online. Additionally, we offer filter features so you can choose a preferred cabin class or airline, see different price ranges, and much more so you can book the flight for you.

Why should you use Cheapflights to find cheap flight tickets from Seattle to Ontario?

It’s simple! Cheapflights, which is free to use for everyone, saves millions of users time and money every year by helping them find the cheapest and most suitable flights from Seattle to Ontario.

Can Cheapflights find flights from Seattle to Ontario with no change fees?

Yes! Cheapflights helps users easily find flights from Seattle to Ontario with no change fees.

Can Cheapflights notify me if prices for flights from Seattle to Ontario become cheaper?

Yes, and it’s super simple to set up. Click the bell icon next to the flight deals above and provide a valid email address to enable Price Alerts. That’s it!

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