Cheapest€128.76
- Frontier Airlines FA891614:122h 46m16:58Seattle SEAOntario ONT
Door to door 5h 56mCO2 394.1 kgChanges 0Fixed, no changes
Seattle to Ontario flight
Flights from Seattle to Ontario start at €154.13 and take 5h 35m at their fastest.
The Flights from Seattle to Ontario starts at €154.13 and takes 5h 35m door to door, run by 4 operators over 1,602 km, with around 24 departures a day. Fares bottom out about 60 days before departure.
- 5h 35mDoor to door
- 2h 25mMoving
- €154.13From
- 394.1 kgCO2
The cheapest and the fastest on September 29, 2026
Two journeys we can sell today, with the service number each operator files them under.
Fastest€185.99
- SkyWest SW535114:122h 25m16:37Seattle SEAOntario ONT
Door to door 5h 35mCO2 394.1 kgChanges 0Fixed, no changes
Airlines
Speed, flexibility and what is on board. Nothing here is a rating, because we have not earned one.
| Operator | From | Fastest |
|---|---|---|
 Alaska Airlines | €131.12 | 5h 35m |
 Frontier Airlines | €128.76 | 5h 36m |
 SkyWest | €137.02 | 5h 35m |
 Bahamasair | €130.53 | 5h 36m |
The flight gets you into Ontario. It does not get you a bed, and neither do we.
Looking for somewhere to stay in Ontario?
Hotels and apartments near downtown, most of them with free cancellation, on a map that shows what is walkable.
Search Ontario on Booking.comOr compare on Expedia
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When to book Seattle to Ontario
The same search run across the whole booking window, so the shape of the curve is visible rather than described.
- €167.7090 days
- €99.8560 days
- €106.9345 days
- €127.5830 days
- €146.4621 days
- €190.1214 days
- €236.737 days
- €242.043 days
- €346.471 days
- Cheapest lead time
- Fares bottom out around 60 days ahead, at €99.85.
- How much it moves
- The gap between the cheapest and most expensive lead time is 247 percent. The most expensive point is €346.47, 1 days out.
- What that means
- Today sits inside the cheap window, which closes about 60 days before departure. Waiting from here has usually cost money on this corridor rather than saved it.
Which departure day costs least
Median cheapest fare for each weekday, taken across the next three weeks of real prices.
- €186.58Sun
- €155.90Mon
- €154.13Tue
- €167.11Wed
- €208.41Thu
- €190.12Fri
- €194.25Sat
Where you leave from and where you arrive
The stations, airports and ports each mode on this corridor actually uses.
Seattle
Air
- SEA
- BFI
Ontario
Air
- ONT
What the journey actually looks like
Direct or connecting, how far the route really runs, and what happens when a connection is missed.
- How far it really runs
- The route covers 1,602 km against 1,556 km in a straight line, a detour of 3 percent. Track and road geometry account for the difference.
- First and last departure
- The first service of the day leaves Seattle at 06:27 and the last at 20:03, across 24 departures. The return direction keeps its own timetable, so the times back are not these times reversed.
Questions about Seattle to Ontario
The questions people actually ask about this trip, answered from the same prices and times the page above is built on rather than written once and left to go stale.
How long does the Flight from Seattle to Ontario take?
The Flight from Seattle to Ontario takes 5h 35m door to door, of which 2h 25m is spent moving. The route runs 1,602 km. The difference between the two times is reaching the terminal and leaving it at the far end, which every time on this page includes.
How much does the Flight from Seattle to Ontario cost?
The Flight from Seattle to Ontario starts at €154.13 for one passenger, checked on September 29, 2026. A typical fare is €157.08. Both are the total including taxes, supplier fees and our service fee, so the price here is the price at checkout.
Who runs the Flight from Seattle to Ontario?
4 operators run the Flight from Seattle to Ontario: Alaska Airlines, Frontier Airlines, SkyWest, Bahamasair. Between them they file around 24 departures a day. The operator table on this page compares them on fare, journey time, cruising speed, fare conditions and what is provided on board.
Which terminal does the Flight from Seattle to Ontario use?
The Flight from Seattle to Ontario leaves from Seattle SEA and arrives at Ontario ONT. Allow about 3h 10m for reaching the departure terminal and leaving the arrival one. That time is already inside every door to door figure quoted on this page.
When should I book the Flight from Seattle to Ontario?
Fares for the Flight from Seattle to Ontario bottom out around 60 days ahead, at €99.85. The gap between the cheapest and most expensive lead time across the window is 247 percent, measured on September 29, 2026. Booking inside the final week has consistently cost more.
How much CO2 does the Flight from Seattle to Ontario produce?
The Flight from Seattle to Ontario produces about 394.1 kg of CO2 per passenger over 1602 km, which works out at roughly 246 grams per passenger kilometer. That figure is for the whole journey and for one traveler, not for the vehicle.
Where these numbers come from
Observed service A carrier record shows this named operator serving this named pair, and we carry that through unchanged.
Schedules, seat counts and fares are generated by our own model until the supplier contracts are signed. Places, coordinates, operators, which operator serves which pair, and every distance are real. We would rather say that on every page than let a modeled number pass for a filed one.
Defined in full at Door to door, Fares, The booking window, Carbon
- On this page
- Every figure above was computed for Seattle to Ontario on September 11, 2026: 1602 km of route against 1556 km in a straight line, 24 services a day, 4 operators, a cheapest fare of €154.13, and 5h 35m door to door on the fastest mode. The return direction is computed separately and its numbers are not these numbers.
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