This is the cheapest round-trip flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 1/10. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ONT
4 Oct — 11 Oct1
Round-trip
1 adult
Economy
Round-trip
1 adult, Economy, 0 bags
Cheapflights Tip: The best prices from Seattle/Tacoma Intl to Ontario are usually found in October or January, booked 74 days in advance, depart on a Friday or Tuesday and return on a Monday
Cheap flight deals from Seattle to Ontario
Enter your travel dates to find the best prices.
Cheapest
Best
Direct
Last-minute
One-way
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 4 September 2026.
Sat 10/107:30 a.m. -
Nonstop2h 47m
Thu 22/102:13 p.m. -
Nonstop2h 43m
Deal found 4/9C$ 217
Thu 29/1010:50 a.m. -
Nonstop2h 48m
Sat 7/116:25 a.m. -
1 stop8h 47m
Deal found 4/9C$ 221
Sun 1/1110:50 a.m. -
Nonstop2h 48m
Sat 7/116:25 a.m. -
1 stop8h 47m
Deal found 4/9C$ 222
Fri 30/109:13 p.m. -
1 stop11h 52m
Sat 7/116:25 a.m. -
1 stop8h 47m
Deal found 4/9C$ 225
Sat 31/107:15 a.m. -
1 stop5h 21m
Fri 6/116:20 a.m. -
Nonstop3h 04m
Deal found 4/9C$ 231
Sat 31/105:30 a.m. -
1 stop7h 06m
Sat 7/111:35 p.m. -
1 stop5h 27m
Deal found 4/9C$ 244
Wed 4/115:40 a.m. -
2 stops8h 50m
Mon 9/118:45 p.m. -
1 stop4h 30m
Deal found 4/9C$ 246
Thu 29/1010:50 a.m. -
Nonstop2h 48m
Mon 2/118:35 p.m. -
1 stop14h 24m
Deal found 4/9C$ 251
Sun 1/1110:50 a.m. -
Nonstop2h 48m
Mon 2/118:35 p.m. -
1 stop14h 24m
Deal found 4/9C$ 253
Thu 29/1010:50 a.m. -
Nonstop2h 48m
Tue 3/1111:52 a.m. -
1 stop27h 20m
Deal found 4/9C$ 265
Thu 22/1010:03 a.m. -
Nonstop2h 50m
Fri 30/105:06 p.m. -
Nonstop3h 02m
Deal found 31/8C$ 266
Fri 9/109:06 p.m. -
Nonstop2h 36m
Mon 19/106:02 a.m. -
Nonstop2h 47m
Deal found 4/9C$ 272
Best flights from Seattle to Ontario
Discover carefully curated flight deals from Seattle to Ontario that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated 4 September 2026.
Sat 31/1010:31 a.m. -
Nonstop2h 45m
Tue 3/1112:02 p.m. -
Nonstop2h 47m
Deal found 4/9C$ 217
Tue 3/117:15 a.m. -
1 stop5h 21m
Tue 3/116:00 p.m. -
Nonstop2h 59m
Deal found 4/9C$ 313
Wed 11/115:15 a.m. -
2 stops6h 40m
Sun 15/115:30 p.m. -
1 stop4h 35m
Deal found 31/8C$ 438
Sat 31/1010:58 a.m. -
1 stop6h 07m
Sun 1/115:59 p.m. -
1 stop5h 01m
Deal found 4/9C$ 341
Sat 17/102:30 p.m. -
Nonstop2h 42m
Tue 20/1011:56 a.m. -
Nonstop2h 59m
Deal found 3/9C$ 341
Wed 13/111:15 a.m. -
Nonstop2h 42m
Wed 20/13:30 p.m. -
Nonstop3h 03m
Deal found 3/9C$ 341
Sun 4/107:30 a.m. -
Nonstop2h 47m
Sat 10/106:02 a.m. -
Nonstop2h 47m
Deal found 1/9C$ 389
Wed 23/98:30 a.m. -
2 stops7h 35m
Sat 26/911:00 a.m. -
2 stops8h 35m
Deal found 2/9C$ 451
Sun 8/1110:05 a.m. -
1 stop6h 58m
Sun 15/115:59 p.m. -
1 stop5h 01m
Deal found 3/9C$ 410
Wed 18/118:25 a.m. -
Nonstop2h 52m
Sat 21/115:59 p.m. -
Nonstop3h 01m
Deal found 3/9C$ 417
Sat 3/107:50 p.m. -
Nonstop2h 50m
Mon 5/106:00 p.m. -
Nonstop2h 50m
Deal found 1/9C$ 467
Sun 1/119:56 a.m. -
1 stop5h 28m
Sun 1/115:59 p.m. -
1 stop5h 01m
Deal found 4/9C$ 509
Direct flights from Seattle to Ontario
Explore direct flight options from Seattle to Ontario based on user searches, and compare prices and availability for your desired travel dates. Data last updated 4 September 2026.
Sat 10/107:30 a.m. -
Nonstop2h 47m
Fri 23/106:56 p.m. -
Nonstop2h 43m
Deal found 4/9C$ 217
Thu 22/1010:03 a.m. -
Nonstop2h 50m
Fri 30/105:06 p.m. -
Nonstop3h 02m
Deal found 31/8C$ 266
Fri 9/109:06 p.m. -
Nonstop2h 36m
Thu 22/102:13 p.m. -
Nonstop2h 43m
Deal found 4/9C$ 272
Sat 3/1010:31 a.m. -
Nonstop2h 45m
Mon 5/106:02 a.m. -
Nonstop2h 47m
Deal found 4/9C$ 275
Sat 17/102:30 p.m. -
Nonstop2h 42m
Tue 20/106:00 p.m. -
Nonstop2h 59m
Deal found 4/9C$ 293
Sun 1/1110:50 a.m. -
Nonstop2h 48m
Fri 6/115:06 p.m. -
Nonstop3h 02m
Deal found 4/9C$ 295
Tue 3/118:34 a.m. -
Nonstop2h 44m
Tue 3/114:09 p.m. -
Nonstop2h 47m
Deal found 4/9C$ 300
Fri 9/1010:53 a.m. -
Nonstop2h 50m
Sun 11/105:15 p.m. -
Nonstop2h 56m
Deal found 2/9C$ 309
Sun 1/1110:50 a.m. -
Nonstop2h 48m
Sun 1/115:06 p.m. -
Nonstop3h 02m
Deal found 4/9C$ 311
Thu 3/128:11 p.m. -
Nonstop2h 48m
Tue 8/127:00 a.m. -
Nonstop3h 05m
Deal found 4/9C$ 313
Sat 3/107:50 p.m. -
Nonstop2h 50m
Mon 5/1011:54 a.m. -
Nonstop2h 56m
Deal found 4/9C$ 316
Sat 3/107:50 p.m. -
Nonstop2h 50m
Wed 14/1011:56 a.m. -
Nonstop2h 59m
Deal found 3/9C$ 341
Last-minute flights from Seattle to Ontario
Discover last-minute flight deals from Seattle to Ontario. Data last updated 4 September 2026 and is based on user searches.
Sat 3/1010:31 a.m. -
Nonstop2h 45m
Mon 5/106:02 a.m. -
Nonstop2h 47m
Deal found 4/9C$ 275
Fri 9/109:06 p.m. -
Nonstop2h 36m
Mon 19/106:02 a.m. -
Nonstop2h 47m
Deal found 4/9C$ 272
Sat 10/107:30 a.m. -
Nonstop2h 47m
Thu 22/102:13 p.m. -
Nonstop2h 43m
Deal found 4/9C$ 217
Thu 22/1010:03 a.m. -
Nonstop2h 50m
Fri 30/105:06 p.m. -
Nonstop3h 02m
Deal found 31/8C$ 266
Wed 28/1012:14 p.m. -
1 stop23h 02m
Sat 7/116:25 a.m. -
1 stop8h 47m
Deal found 4/9C$ 282
Thu 29/1010:50 a.m. -
Nonstop2h 48m
Sat 7/116:25 a.m. -
1 stop8h 47m
Deal found 4/9C$ 221
Thu 29/1010:50 a.m. -
Nonstop2h 48m
Mon 2/118:35 p.m. -
1 stop14h 24m
Deal found 4/9C$ 251
Thu 29/1010:50 a.m. -
Nonstop2h 48m
Tue 3/1111:52 a.m. -
1 stop27h 20m
Deal found 4/9C$ 265
Fri 30/109:13 p.m. -
1 stop11h 52m
Sat 7/116:25 a.m. -
1 stop8h 47m
Deal found 4/9C$ 225
Fri 30/109:13 p.m. -
1 stop11h 52m
Fri 6/115:06 p.m. -
Nonstop3h 02m
Deal found 4/9C$ 280
Sat 31/107:15 a.m. -
1 stop5h 21m
Fri 6/116:20 a.m. -
Nonstop3h 04m
Deal found 4/9C$ 231
Sat 31/106:50 a.m. -
1 stop6h 10m
Wed 4/113:30 p.m. -
1 stop6h 00m
Deal found 4/9C$ 244
One-way flights from Seattle to Ontario
Search for one-way flight options from Seattle to Ontario. Find affordable one-way fares based on user searches. Data last updated 4 September 2026.
Thu 1/106:55 a.m. -
1 stop5h 05m
Wed 31/1212:00 a.m. -
Nonstop0h 00m
Deal found 4/9C$ 123
Sat 3/109:45 a.m. -
1 stop8h 10m
Wed 31/1212:00 a.m. -
Nonstop0h 00m
Deal found 4/9C$ 130
Tue 6/108:25 a.m. -
Nonstop2h 51m
Wed 31/1212:00 a.m. -
Nonstop0h 00m
Deal found 4/9C$ 150
Tue 10/117:45 a.m. -
1 stop4h 10m
Wed 31/1212:00 a.m. -
Nonstop0h 00m
Deal found 30/8C$ 178
Wed 14/101:19 p.m. -
1 stop7h 12m
Wed 31/1212:00 a.m. -
Nonstop0h 00m
Deal found 3/9C$ 185
Wed 14/1012:05 p.m. -
2 stops7h 35m
Wed 31/1212:00 a.m. -
Nonstop0h 00m
Deal found 31/8C$ 192
Tue 1/128:05 a.m. -
1 stop5h 10m
Wed 31/1212:00 a.m. -
Nonstop0h 00m
Deal found 1/9C$ 199
Sat 10/107:56 p.m. -
Nonstop2h 47m
Wed 31/1212:00 a.m. -
Nonstop0h 00m
Deal found 2/9C$ 213
Wed 3/311:20 a.m. -
1 stop5h 55m
Wed 31/1212:00 a.m. -
Nonstop0h 00m
Deal found 2/9C$ 220
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 4 September 2026.
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 7,457,451 searches. Data last updated 4 September 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 Seattle/Tacoma Intl - ONT Ontario
SEAONT
Seattle/Tacoma Intl
Thu 29/10
10:58 a.m.-5:05 p.m.
1 stop6h 07m
Ontario
Wed 31/12
12:00 a.m.-12:00 a.m.
Nonstop0h 00m
C$ 206
SeattleOntario
SEA Seattle/Tacoma Intl - ONT Ontario
SEAONT
Seattle/Tacoma Intl
Wed 28/10
2:30 p.m.-5:12 p.m.
Nonstop2h 42m
Ontario
Wed 31/12
12:00 a.m.-12:00 a.m.
Nonstop0h 00m
C$ 213
SeattleOntario
SEA Seattle/Tacoma Intl - ONT Ontario
SEAONT
Seattle/Tacoma Intl
Tue 6/10
8:25 a.m.-11:16 a.m.
Nonstop2h 51m
Ontario
Wed 31/12
12:00 a.m.-12:00 a.m.
Nonstop0h 00m
C$ 213
Quickest round-trip
SeattleOntario
SEA Seattle/Tacoma Intl - ONT Ontario
SEAONT
Seattle/Tacoma Intl
Tue 5/1
8:05 p.m.-10:41 p.m.
Nonstop2h 36m
Ontario
Wed 31/12
12:00 a.m.-12:00 a.m.
Nonstop0h 00m
C$ 213
SeattleOntario
SEA Seattle/Tacoma Intl - ONT Ontario
SEAONT
Seattle/Tacoma Intl
Sat 31/10
10:31 a.m.-1:16 p.m.
Nonstop2h 45m
Ontario
Tue 3/11
12:02 p.m.-2:49 p.m.
Nonstop2h 47m
C$ 217
SeattleOntario
SEA Seattle/Tacoma Intl - ONT Ontario
SEAONT
Seattle/Tacoma Intl
Thu 1/10
7:11 a.m.-12:18 p.m.
1 stop5h 07m
Ontario
Wed 31/12
12:00 a.m.-12:00 a.m.
Nonstop0h 00m
C$ 220
SeattleOntario
SEA Seattle/Tacoma Intl - ONT Ontario
SEAONT
Seattle/Tacoma Intl
Sat 31/10
10:31 a.m.-1:16 p.m.
Nonstop2h 45m
Ontario
Wed 31/12
12:00 a.m.-12:00 a.m.
Nonstop0h 00m
C$ 226
SeattleOntario
SEA Seattle/Tacoma Intl - ONT Ontario
SEAONT
Seattle/Tacoma Intl
Fri 30/10
2:10 p.m.-9:25 p.m.
2 stops7h 15m
Ontario
Wed 31/12
12:00 a.m.-12:00 a.m.
Nonstop0h 00m
C$ 242
SeattleOntario
SEA Seattle/Tacoma Intl - ONT Ontario
SEAONT
Seattle/Tacoma Intl
Sat 3/10
7:50 a.m.-4:00 p.m.
2 stops8h 10m
Ontario
Wed 31/12
12:00 a.m.-12:00 a.m.
Nonstop0h 00m
C$ 268
SeattleOntario
SEA Seattle/Tacoma Intl - ONT Ontario
SEAONT
Seattle/Tacoma Intl
Tue 29/12
8:31 a.m.-11:10 a.m.
Nonstop2h 39m
Ontario
Wed 31/12
12:00 a.m.-12:00 a.m.
Nonstop0h 00m
C$ 289
Flights are sorted by cheapest round-trip flights first.
Deals found on 31/8
Showing 1-10 of 22 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.
SEA-ONT
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
Prices
Airlines
How far ahead should I book a flight from Seattle to Ontario?
Booking 73 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, October is the cheapest month in which you can book a flight from Seattle to Ontario (average of C$ 276). Flying from Seattle to Ontario in February is currently the most expensive (average of C$ 516). 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 4 September 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 53% on airfare.
How much does it cost to fly round-trip from Seattle to Ontario?
Airfare is below average for this route at the moment.
Seattle to Ontario flights typically cost between C$ 242 and C$ 442 in October.The cheapest round-trip price found within the last 5 days was C$ 217 on Delta (10 Oct-17 Oct).
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 4 September 2026.
The most flights from SEA to ONT are scheduled on a Thursday (22 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (3 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 4 September 2026.
Read reviews from past customers who have flown Alaska Airlines and 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.
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?
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 36m on average. When it comes time to book airfare, you have a few options: there are 12 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, 28 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$ 217, Alaska Airlines can have you in Ontario from Seattle in 2h 45m. Seattle and Ontario are separated by a distance of 1539 km. This flight may include one or multiple stops.
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$ 166. Another airline that can offer you cheap pricing is Alaska Airlines. Frontier is currently priced 57% 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: Scandinavian Airlines (94%), Virgin Atlantic (90%), Frontier (84%).
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$ 399, our data indicates the cheapest price to be C$ 205. The most popular route (Seattle/Tacoma Intl - Ontario), is priced around C$ 323.
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 C$ 276). Flying from Seattle to Ontario in February is currently the most expensive (average of C$ 516). 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.
Explore flights to Ontario departing from other origins. Flights are based on user searches made on Cheapflights and were last updated on 4 September 2026.
Browse through other flights departing from Seattle. Flights are based on user searches made on Cheapflights and were last updated on 4 September 2026.
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 7,457,451 searches. Data last updated 4 September 2026.
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.
We value your privacy
Cheapflights and its partners wish to use cookies or similar technologies to store and/or access information on and about your device and process personal data such as your IP address, device identifiers etc., in order to improve your experience on the site, to analyze navigation, to offer and measure personalized advertising, and to facilitate sharing on social networks. We also allow the use of third-party cookies (including those from our advertising partners) on our sites.
By clicking 'Accept', you consent to your data being processed by 0 vendors on this web site for the purposes described in this notice. You can review the vendors and their individual processing purposes on the .
To review individual processing purposes and cookie categories, please click ’Select individual purposes’. You can review and update your choices anytime by clicking the ’Privacy Preferences’ link in the page side navigation.