Find flights
Deals
When to book
Airlines
FAQs

Cheap flights from Seattle to Ontario from C$ 134

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 10/5. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ONT
10 Apr — 17 Apr1
1 adult
1 adult, Economy, 0 bags
Cheapflights Tip: The best prices from Seattle/Tacoma Intl to Ontario are usually found in October or September, booked 75 days in advance, depart on a Saturday or Friday and return on a Wednesday

Cheap flight deals from Seattle to Ontario

Enter your travel dates to find the best prices.

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 11 March 2026.

Sat 2/55:45 a.m.
SEA
-
ONT
2 stops9h 50m
Southwest
Thu 7/56:00 p.m.
ONT
-
SEA
1 stop6h 55m
Southwest
Deal found 9/3C$ 212
Tue 31/37:50 p.m.
SEA
-
ONT
Nonstop2h 44m
Delta
Sat 4/411:59 a.m.
ONT
-
SEA
Nonstop2h 56m
Delta
Deal found 7/3C$ 213
Wed 22/410:54 a.m.
SEA
-
ONT
Nonstop2h 45m
Delta
Mon 27/411:53 a.m.
ONT
-
SEA
Nonstop3h 04m
Delta
Deal found 6/3C$ 215
Sun 10/58:25 a.m.
SEA
-
ONT
Nonstop2h 47m
Delta
Wed 13/51:35 p.m.
ONT
-
SEA
Nonstop3h 00m
Delta
Deal found 10/3C$ 216
Tue 28/48:25 a.m.
SEA
-
ONT
2 stops7h 25m
Southwest
Tue 5/53:45 p.m.
ONT
-
SEA
2 stops7h 10m
Southwest
Deal found 6/3C$ 219
Fri 1/55:30 a.m.
SEA
-
ONT
1 stop7h 40m
Southwest
Tue 5/53:45 p.m.
ONT
-
SEA
2 stops7h 10m
Southwest
Deal found 5/3C$ 220
Thu 23/49:17 p.m.
SEA
-
ONT
Nonstop2h 42m
Alaska Airlines
Sat 25/410:39 a.m.
ONT
-
SEA
Nonstop2h 51m
Alaska Airlines
Deal found 9/3C$ 227
Sat 25/411:10 a.m.
SEA
-
ONT
1 stop5h 15m
Delta
Mon 27/42:20 p.m.
ONT
-
SEA
Nonstop3h 04m
Delta
Deal found 8/3C$ 228
Sun 10/57:50 p.m.
SEA
-
ONT
Nonstop2h 44m
Delta
Tue 12/54:57 p.m.
ONT
-
SEA
1 stop5h 06m
Delta
Deal found 10/3C$ 229
Fri 17/41:55 p.m.
SEA
-
ONT
1 stop8h 45m
Southwest
Sat 25/43:35 p.m.
ONT
-
SEA
1 stop7h 25m
Southwest
Deal found 10/3C$ 232
Mon 13/410:58 p.m.
SEA
-
ONT
2 stops13h 16m
Delta
Tue 21/47:00 a.m.
ONT
-
SEA
Nonstop3h 07m
Delta
Deal found 9/3C$ 234
Wed 22/47:50 a.m.
SEA
-
ONT
1 stop5h 55m
Southwest
Wed 29/44:30 p.m.
ONT
-
SEA
2 stops6h 25m
Southwest
Deal found 10/3C$ 239

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 11 March 2026.

Round-trip from

C$ 212

One-way from

C$ 134

Popular in

February

Cheapest in

October

Average price

C$ 323
Southwest
  • Southwest
  • 2/5-7/5
  • 3 total stops
  • 16h 45m total
  • Seattle to Ontario
Search Deals
Alaska Airlines
  • Alaska Airlines
  • 30/3
  • 1 total stop
  • 7h 16m total
  • Seattle to Ontario
Search Deals
Highest demand for flights based on searches. 12% potential increase in price (C$ 64 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 4% potential price decrease (C$ 23 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in March 2026
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 629,999 searches. Data last updated 11 March 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

Sun 10/5

8:25 a.m.-11:12 a.m.

Nonstop2h 47m

Ontario

Wed 13/5

1:35 p.m.-4:35 p.m.

Nonstop3h 00m

C$ 216

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Mon 11/5

8:25 a.m.-11:12 a.m.

Nonstop2h 47m

Ontario

Thu 14/5

1:35 p.m.-4:35 p.m.

Nonstop3h 00m

C$ 216

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 24/3

4:55 p.m.-11:51 p.m.

1 stop6h 56m

Ontario

Wed 1/4

5:53 p.m.-8:50 p.m.

Nonstop2h 57m

C$ 363

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Wed 25/3

8:26 a.m.-3:42 p.m.

1 stop7h 16m

Ontario

Wed 1/4

7:08 p.m.-9:57 p.m.

Nonstop2h 49m

C$ 376

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 28/3

8:26 a.m.-3:42 p.m.

1 stop7h 16m

Ontario

Sat 4/4

4:22 p.m.-8:58 p.m.

1 stop4h 36m

C$ 384

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Wed 25/3

7:15 a.m.-12:18 p.m.

1 stop5h 03m

Ontario

Wed 1/4

6:49 p.m.-11:27 p.m.

1 stop4h 38m

C$ 403

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Thu 2/4

8:26 a.m.-3:42 p.m.

1 stop7h 16m

Ontario

Mon 6/4

7:08 p.m.-9:57 p.m.

Nonstop2h 49m

C$ 407

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 21/3

9:24 p.m.-11:59 p.m.

Nonstop2h 35m

Ontario

Tue 31/3

4:22 p.m.-8:58 p.m.

1 stop4h 36m

C$ 410
Quickest round-trip

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 21/3

9:24 p.m.-11:59 p.m.

Nonstop2h 35m

Ontario

Wed 25/3

10:33 a.m.-1:23 p.m.

Nonstop2h 50m

C$ 430

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 21/3

9:24 p.m.-11:59 p.m.

Nonstop2h 35m

Ontario

Thu 26/3

6:00 a.m.-8:54 a.m.

Nonstop2h 54m

C$ 458

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/3

Showing 1-10 of 23 resultsSorted by cheapest first
1
2
3

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 6 March 2026.

Booking 75 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, June is the cheapest month in which you can book a flight from Seattle to Ontario (average of C$ 75). Flying from Seattle to Ontario in July is currently the most expensive (average of C$ 162). 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 11 March 2026.

One of the essential ways to save on airfare from Seattle to Ontario is to remain as flexible as possible. Flights that are at noon tend to be the most expensive. A flight in the afternoon could potentially save you up to 44% on airfare.

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 11 March 2026.
Read reviews from past customers who have flown Frontier 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.
Frontier
5.7
Fair
3,034 reviews
Check prices

Food

4.6

Overall

5.7

Entertainment

4.3

Comfort

5.5

Crew

6.6

Boarding

6.0

Reviews

1 / 20
10.0
Excellent

Anonymous,Feb 2026

BOS - ATL

Everything was on time. There were no refreshments but that was known in advance. Crew managed a medical emergency with efficiency and care.
Frontier
5.7
Fair
3,034 reviews
Frontier
5.7
Fair
3,034 reviews
Check prices

Food

4.6

Overall

5.7

Entertainment

4.3

Comfort

5.5

Crew

6.6

Boarding

6.0

Reviews

1 / 20
10.0
Excellent

Anonymous,Feb 2026

BOS - ATL

Everything was on time. There were no refreshments but that was known in advance. Crew managed a medical emergency with efficiency and care.

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 35m on average. When it comes time to book airfare, you have a few options: there are 13 outbound flights from Seattle/Tacoma Intl to Ontario offered by 1 airline.

  • How popular is this Seattle to Ontario flight route?

    Within the past month, 11 users have taken a look at flights from Seattle/Tacoma Intl to Ontario.

  • How long is the flight from Seattle to Ontario?

    For as low as C$ 216, Delta can have you in Ontario from Seattle in 2h 47m. Seattle and Ontario are separated by a distance of 1539 km. This flight may include one or multiple stops.

  • What is the cheapest airline to fly from Seattle to Ontario round-trip?

    Cheapflights users have booked flights from Seattle to Ontario round-trip from C$ 163. Frontier is currently priced 52% below the average price you’ll pay for this route.

  • 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: Frontier (100%), Volaris (100%), Korean Air (87%).

  • 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, June is the cheapest month in which you can book a flight from Seattle to Ontario (average of C$ 75). Flying from Seattle to Ontario in July is currently the most expensive (average of C$ 162). 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

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Top airline flying from Seattle to Ontario

Discover the top airline 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 11 March 2026.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapestC$ 163AverageC$ 301FlexibilityNo cancel feeOn-time62%
Search Frontier 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!

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.