Seattle to Ontario flights
The cheapest round trip we found from Seattle to Ontario is $175 (Dec 10 – 14, Nonstop), 20% below the usual $220.
SEA to ONT · Round trip · Economy · Prices per person in USD · Price found (1 day ago)
Cheapest found
Cheapest round trip by month
Lowest fare found per departure month| Month | Cheapest round trip |
|---|---|
| November 2026 | $270 |
| December 2026 | $146 (cheapest month) |
| January 2027 | $281 |
Cheapest dates in the next 4 months
Round trip, per person-
Dec 10 – 14 4 nights · leave Thu$175 −20% vs usual$175 −20% vs usual Book
Alaska Airlines Nonstop · 2h 32m -
Dec 13 – 17 4 nights · leave Sun$210 −5% vs usual$210 −5% vs usual Book
Frontier Airlines 1 stop · 3h 44m -
Dec 2 – 12 10 nights · leave Wed$229$229 Book
Frontier Airlines 1 stop · 5h 13m
-
Jan 14 – 16, 2027 2 nights · leave Thu$281 +28% vs usual$281 +28% vs usual Book
Frontier Airlines 1 stop · 3h 45m
-
Nov 29 – Dec 2 3 nights · leave Sun$290 +32% vs usual$290 +32% vs usual Book
Frontier Airlines 1 stop · 2h 48m
-
Nov 17 – 20 3 nights · leave Tue$461 +110% vs usual$461 +110% vs usual Book
United Airlines 1 stop · 3h 40m
Prices change often. The booking site shows the final price before you pay. Other dates? Set an alert
Plan the rest of your trip
Ontario · Dec 10 – 14- Car rental Economybookings · compare rental companies (opens Economybookings in a new tab)
- Things to do in Ontario Klook · tours and tickets (opens Klook in a new tab)
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Good to know
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Seattle to Ontario: questions
How much does a flight from Seattle to Ontario cost?
The cheapest round trip we have found right now is $175, leaving December 10 and returning December 14. The usual price on this route is about $220, so this fare is 20% less. Prices are per person, economy, in USD.
What is the cheapest month to fly from Seattle to Ontario?
December 2026, with round trips from $146. The most expensive month in our data is January (from $281). Based on the 3 months ahead we have prices for.
Which airports do Seattle to Ontario flights use?
Seattle airports include Seattle-Tacoma International (SEA) and Boeing Field International (BFI). Ontario airports include Ontario International (ONT). The prices on this page cover every airport in both cities (SEA and ONT are the city codes).
About this route
We track round-trip economy fares from Seattle (United States) to Ontario (United States) using Travelpayouts / Aviasales data. The cheapest round trip we've found is $175, departing December 10 and returning December 14 on a nonstop flight, about 20% below the usual $220. Right now we're following 6 upcoming date combinations on this route. The cheapest month to fly in our data is December, from $146. Prices are per person and were correct when found; the final price is set by the airline or booking site when you book.