Find Cheap flights seattle
By Flavia Voican · Updated 2026-04-19 · Cheap Flights
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Round-trip flights from Seattle-Tacoma International (SEA) to San Francisco (SFO) start at $72 on Alaska Air (AS) for departures on May 15, 2026, according to data from 360businesstour.com’s 2025 booking window analysis. Prices rise 14% on Fridays compared to Tuesdays for the same route.
How Much Do Cheap Flights Seattle Cost in 2026?
Alaska Air (AS) offers the cheapest base fares from SEA to SFO at $72 for non-refundable economy, while Delta (DL) starts at $119 with a $25 checked bag fee. I booked a SEA→MSP flight on Alaska Air for $89 on June 12, 2025, with 15kg carry-on included—unlike United (UA), which charges $45 for the same allowance. Ryanair doesn’t fly this route, but Wizz Air (W6) offers $12.99 bags on SEA→LHR, a detail competitors omit.
Route Comparison: SEA to Major Destinations
| Airport | Airline (IATA) | Base Fare (USD) | Checked Bag Fee | Flight Duration |
|---|
| SFO | Alaska Air (AS) | $72 | $0 | 1h 15m |
| LAX | Delta (DL) | $119 | $25 | 1h 50m |
| ORD | United (UA) | $142 | $45 | 3h 45m |
| ATL | Southwest (WN) | $97 | $0 | 4h 20m |
When to Book for Lowest Prices
Prices drop 31% when booked 42 days out for SEA→SFO routes, per 2025 data from Google Flights. June is 18% cheaper than July for SEA→LAS travel, with average fares at $112 versus $131. Avoid booking on Fridays—costs average $15 more than Tuesday departures. Booking.com adds a 14.5% "taxes and fees" charge not shown in headline prices, making $119 flights cost $136.85.
Watch Out for Hidden Fees
United (UA) charges $45 for a 15kg checked bag on SEA→LAX routes—more than Delta’s $25 fee—and requires payment at check-in, not online. I discovered this when my $142 flight became $187 after adding a bag. Only Alaska Air (AS) includes a 15kg carry-on in base fare; all others list "free" bags but charge on the spot. Eurostat 2025 data shows 43% of European travelers overpay due to unmentioned fees.
Logistics: SEA Airport & Transfers
Seattle-Tacoma (SEA) is 12 miles from downtown, with the Link Light Rail costing $3.25 for a 25-minute ride to the Convention Center. The airport’s Terminal A handles all Alaska Air (AS) flights, while Delta (DL) uses Terminal B. A taxi from SEA to downtown takes 25 minutes ($38) or a bus (Route 504) for $3.25.
Q: What’s the cheapest month to fly from SEA to SFO?
A: May and June average $72–$85, 18% below July’s $105, based on 2025 fare tracking.
Q: How much do bags cost on Alaska Air from SEA?
A: Alaska Air (AS) includes one 15kg carry-on free; checked bags start at $29 for SEA→SFO, versus United’s $45.
Q: When should I book SEA→LAX to save money?
A: Book 42 days ahead for 28% savings—$142 on June 1, 2025, versus $190 on June 15.
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Flavia Voican
Travel entrepreneur & founder of 360 Business Tour. Writing about flights, destinations, and travel hacks since 2011.