$129 Cheap Delta flights Philadelphia (PHL) to Seattle (SEA)

Finding cheap one-way Delta Air Lines flights from PHL to SEA from $129 on Expedia is easy --- just filter by "Price (lowest to highest)." Or check out our affordable return fares from $277 for your next break.**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.

Begin your search one to three months before your departure to find cheap fares on Delta Air Lines flights from Philadelphia Intl. Airport (PHL) to Seattle - Tacoma Intl. Airport (SEA). You can save 25% by booking your domestic flight 34 to 86 days in advance versus last-minute reservations made 6 to 12 days out. You could also cut costs by buying your fare on a Sunday, as it's 6% cheaper on average than a Monday, the most expensive day to book.* Get the timing right, and you can enjoy significant savings on domestic journeys.*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.

Find Delta Air Lines's earliest flights from PHL to SEA by selecting our "Morning" and "Early Morning" filters. Not only will you arrive at your destination sooner, early departures also experience 20% fewer 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.

With an excellent in-flight experience and a rewarding loyalty program, Delta Air Lines is a popular option for many passengers heading from PHL to SEA. Also, if you're a Delta SkyMiles and One Key™ member booking through Expedia, you could earn OneKeyCash™* on eligible flights on top of your airline miles, which can be put toward future travel.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.