$562 Cheap Spirit Airlines flights Boston (BOS) to Seattle (SEA)

Grab budget-friendly return Spirit Airlines flights from $737 from BOS to SEA by organizing your results from "Price (lowest to highest)" on Expedia. Or search for bargains from $562 for a one-way journey.**These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply.

For cheap Spirit Airlines fares from Logan Intl. Airport (BOS) to Seattle - Tacoma Intl. Airport (SEA), start searching one to three months before your planned departure. Reserving domestic flights 34 to 86 days in advance could save you 25% compared to booking just 6 to 12 days ahead. The day you book can also influence the overall price. Sunday is generally the cheapest, while Monday is often the most expensive for domestic flights. You can save 6% on average by booking your trip on a Sunday.**Ideal booking window recommendation is based on average round-trip ticket prices for January through November for 2024. Best day of the week to book recommendation is based on average round-trip ticket prices for January through October 2024. All data sourced from ARC's global airline sales database.

Filter your results by "Early Morning" and "Morning" to browse the earliest departures from BOS to SEA. Taking off early means you're 20% less likely to experience cancellations.**Most reliable time of the day recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.

A rewarding loyalty program and the ability to collect points through Free Spirit are the start of the reasons to fly from BOS to SEA with Spirit Airlines. Plus, when you sign up to our One Key™ program, you can earn OneKeyCash™* on top of Spirit Airlines's loyalty program earnings. It's yours to spend on future bookings.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.