Seattle to Ontario flights
Routavio compares airline fares from several flight booking sites. The lowest one-way fare it found for Seattle to Ontario is €81 with Frontier Airlines (checked on 5 Nov 2026).
Your next trip, last seen at €81
Lowest observedFrontier Airlines · 1 stop · One wayWhen to fly
Explore datesMore dates worth a look
Last seen for 1 traveller on 12 Nov 2026. Check today's price.
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The lowest fare we observed for each month. Open a month to see its days, then pick your outbound and return. A day with no price is one we will search for you.
One-way fare
- Lowest observed
- €81, departing 22 Feb 2027 (Last checked: 5 Nov 2026)One-way fare · Priced departure days checked in the last 14 days: 12Check live prices for this route
- Round trip
- €132, departing 11 Dec 2026, back 13 Dec 2026 (Last checked: 12 Nov 2026)
- Non-stop, one way
- €127, departing 2 Jan 2027 (Last checked: 6 Nov 2026)
- Airlines seen
- Alaska Airlines, Delta Air Lines, Frontier Airlines, Southwest Airlines, United Airlines
- Fastest observed flight time
- 2h 34m
- Non-stop
- Yes
About this route
Explore the fares we observed from Seattle to Ontario. Prices move often, so pick your dates to see the latest options.
- Route distance
- 1,557 km
- Fastest observed flight time
- 2h 34m
- Airlines seen
- Alaska Airlines, Delta Air Lines, Frontier Airlines, Southwest Airlines, United Airlines
- Alternative airports
- BFI
Route-level information; individual journeys vary.
A clearer picture of your fare
If the observed fare for this date drops, we will email you. At most one message a day.
Airport to city: straight-line distance
- King County International Airport - Boeing Field (BFI) → Seattle, city gazetteer reference point (47.6062, -122.3321): ≈ 9 km.
- Seattle–Tacoma International Airport (SEA) → Seattle, city gazetteer reference point (47.6062, -122.3321): ≈ 18 km.
- Ontario International Airport (ONT) → Ontario, city gazetteer reference point (34.0500, -117.6400): ≈ 4 km.
Approximate distances calculated from coordinates, not road distances or travel times. These airports serve the city; they are not confirmed endpoints of an offer.
Observed fares by departure date
| Departure | Fare | Seen on |
|---|---|---|
| €123 | 5 Nov 2026 | |
| €160 | 5 Nov 2026 | |
| €191 | 12 Nov 2026 | |
| €191 | 12 Nov 2026 | |
| €218 | 8 Nov 2026 | |
| €167 | 11 Nov 2026 | |
| €167 | 12 Nov 2026 | |
| €167 | 12 Nov 2026 | |
| €167 | 12 Nov 2026 | |
| €167 | 12 Nov 2026 | |
| €167 | 12 Nov 2026 | |
| €167 | 12 Nov 2026 | |
| €167 | 12 Nov 2026 | |
| €168 | 11 Nov 2026 | |
| €92 | 5 Nov 2026 | |
| €92 | 5 Nov 2026 | |
| €107 | 5 Nov 2026 | |
| €85 | 5 Nov 2026 | |
| €92 | 5 Nov 2026 | |
| €81 | 5 Nov 2026 |
One-way fares. Each row is one price we saw for that departure day on the date shown, not a guaranteed fare.
Lowest fare by days before departure
Lowest fare from Seattle to Ontario by days until departure (0 to 7 days): €167 (checked 11 Nov 2026).
| Days before departure | Lowest fare | Priced days |
|---|---|---|
| 0 to 7 days | €167 | 6 |
| 8 to 30 days | €167 | 6 |
One-way fares checked in the last 14 days. Each figure is the lowest stored fare for that distance to departure, not a price forecast.
Fares for different departure dates, checked now; not a guide to when to book.
Lowest one-way fare we saw per airline
Cheapest airline from Seattle to Ontario: Frontier Airlines, €81 (checked 6 Nov 2026).
| Airline | Lowest fare | Priced days |
|---|---|---|
| Frontier Airlines | €81Feb 22, 2027 | 60 |
| Alaska Airlines | €117Feb 23, 2027 | 19 |
One-way fares checked in the last 14 days. An airline listed here had a fare on at least 3 departure days. Each figure is the lowest we saw, not a guaranteed fare. Connecting itineraries are included; the date is the departure day of that fare.
Frequently asked
How much is a flight from Seattle to Ontario?
The lowest fare Routavio has observed is €81, found on 5 Nov 2026.
Are there direct flights from Seattle to Ontario?
Yes. Published schedules report non-stop flights on this route with Alaska Airlines, Delta Air Lines, Frontier Airlines, Southwest Airlines.
Which airlines fly from Seattle to Ontario?
Routavio has seen these carriers on the route: Alaska Airlines, Delta Air Lines, Frontier Airlines, Southwest Airlines, United Airlines.
How long does the flight from Seattle to Ontario take?
Across the 75 fares Routavio observed, the average journey time is 10h 02m, including any stops. Individual departures vary; the fastest observed flight is listed in the route facts above.
How many of the observed Seattle to Ontario fares were non-stop?
4 of the 80 fares we observed were non-stop; the rest included at least one stop. That describes our observations, not every flight that operates.
How much is a round trip from Seattle to Ontario?
Cheapest round trip: €132, departing 11 Dec 2026, back 13 Dec 2026 (checked 12 Nov 2026).
How much is a non-stop flight from Seattle to Ontario?
Cheapest non-stop one-way fare: €127, departing 2 Jan 2027 (checked 6 Nov 2026).
Which airline has the lowest fare from Seattle to Ontario?
Cheapest airline from Seattle to Ontario: Frontier Airlines, €81 (checked 6 Nov 2026).
How observed prices work, what "No data" means and what a fare includes: Read the flight price guide · Price and schedule freshness on Routavio
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Recently observed fares. Prices may change.